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Diffstat (limited to 'compiler/rustc_hir_analysis/src/collect.rs')
| -rw-r--r-- | compiler/rustc_hir_analysis/src/collect.rs | 3403 |
1 files changed, 3403 insertions, 0 deletions
diff --git a/compiler/rustc_hir_analysis/src/collect.rs b/compiler/rustc_hir_analysis/src/collect.rs new file mode 100644 index 00000000000..e7deae2b557 --- /dev/null +++ b/compiler/rustc_hir_analysis/src/collect.rs @@ -0,0 +1,3403 @@ +//! "Collection" is the process of determining the type and other external +//! details of each item in Rust. Collection is specifically concerned +//! with *inter-procedural* things -- for example, for a function +//! definition, collection will figure out the type and signature of the +//! function, but it will not visit the *body* of the function in any way, +//! nor examine type annotations on local variables (that's the job of +//! type *checking*). +//! +//! Collecting is ultimately defined by a bundle of queries that +//! inquire after various facts about the items in the crate (e.g., +//! `type_of`, `generics_of`, `predicates_of`, etc). See the `provide` function +//! for the full set. +//! +//! At present, however, we do run collection across all items in the +//! crate as a kind of pass. This should eventually be factored away. + +use crate::astconv::AstConv; +use crate::bounds::Bounds; +use crate::check::intrinsic::intrinsic_operation_unsafety; +use crate::constrained_generic_params as cgp; +use crate::errors; +use crate::middle::resolve_lifetime as rl; +use rustc_ast as ast; +use rustc_ast::{MetaItemKind, NestedMetaItem}; +use rustc_attr::{list_contains_name, InlineAttr, InstructionSetAttr, OptimizeAttr}; +use rustc_data_structures::captures::Captures; +use rustc_data_structures::fx::{FxHashMap, FxHashSet, FxIndexSet}; +use rustc_errors::{struct_span_err, Applicability, DiagnosticBuilder, ErrorGuaranteed, StashKey}; +use rustc_hir as hir; +use rustc_hir::def::{CtorKind, DefKind}; +use rustc_hir::def_id::{DefId, LocalDefId, LOCAL_CRATE}; +use rustc_hir::intravisit::{self, Visitor}; +use rustc_hir::weak_lang_items; +use rustc_hir::{GenericParamKind, HirId, Node}; +use rustc_middle::hir::nested_filter; +use rustc_middle::middle::codegen_fn_attrs::{CodegenFnAttrFlags, CodegenFnAttrs}; +use rustc_middle::mir::mono::Linkage; +use rustc_middle::ty::query::Providers; +use rustc_middle::ty::subst::InternalSubsts; +use rustc_middle::ty::util::Discr; +use rustc_middle::ty::util::IntTypeExt; +use rustc_middle::ty::{self, AdtKind, Const, DefIdTree, IsSuggestable, Ty, TyCtxt}; +use rustc_middle::ty::{ReprOptions, ToPredicate}; +use rustc_session::lint; +use rustc_session::parse::feature_err; +use rustc_span::symbol::{kw, sym, Ident, Symbol}; +use rustc_span::{Span, DUMMY_SP}; +use rustc_target::spec::{abi, SanitizerSet}; +use rustc_trait_selection::traits::error_reporting::suggestions::NextTypeParamName; +use std::iter; + +mod item_bounds; +mod type_of; + +#[derive(Debug)] +struct OnlySelfBounds(bool); + +/////////////////////////////////////////////////////////////////////////// +// Main entry point + +fn collect_mod_item_types(tcx: TyCtxt<'_>, module_def_id: LocalDefId) { + tcx.hir().visit_item_likes_in_module(module_def_id, &mut CollectItemTypesVisitor { tcx }); +} + +pub fn provide(providers: &mut Providers) { + *providers = Providers { + opt_const_param_of: type_of::opt_const_param_of, + type_of: type_of::type_of, + item_bounds: item_bounds::item_bounds, + explicit_item_bounds: item_bounds::explicit_item_bounds, + generics_of, + predicates_of, + predicates_defined_on, + explicit_predicates_of, + super_predicates_of, + super_predicates_that_define_assoc_type, + trait_explicit_predicates_and_bounds, + type_param_predicates, + trait_def, + adt_def, + fn_sig, + impl_trait_ref, + impl_polarity, + is_foreign_item, + generator_kind, + codegen_fn_attrs, + asm_target_features, + collect_mod_item_types, + should_inherit_track_caller, + ..*providers + }; +} + +/////////////////////////////////////////////////////////////////////////// + +/// Context specific to some particular item. This is what implements +/// [`AstConv`]. +/// +/// # `ItemCtxt` vs `FnCtxt` +/// +/// `ItemCtxt` is primarily used to type-check item signatures and lower them +/// from HIR to their [`ty::Ty`] representation, which is exposed using [`AstConv`]. +/// It's also used for the bodies of items like structs where the body (the fields) +/// are just signatures. +/// +/// This is in contrast to [`FnCtxt`], which is used to type-check bodies of +/// functions, closures, and `const`s -- anywhere that expressions and statements show up. +/// +/// An important thing to note is that `ItemCtxt` does no inference -- it has no [`InferCtxt`] -- +/// while `FnCtxt` does do inference. +/// +/// [`FnCtxt`]: crate::check::FnCtxt +/// [`InferCtxt`]: rustc_infer::infer::InferCtxt +/// +/// # Trait predicates +/// +/// `ItemCtxt` has information about the predicates that are defined +/// on the trait. Unfortunately, this predicate information is +/// available in various different forms at various points in the +/// process. So we can't just store a pointer to e.g., the AST or the +/// parsed ty form, we have to be more flexible. To this end, the +/// `ItemCtxt` is parameterized by a `DefId` that it uses to satisfy +/// `get_type_parameter_bounds` requests, drawing the information from +/// the AST (`hir::Generics`), recursively. +pub struct ItemCtxt<'tcx> { + tcx: TyCtxt<'tcx>, + item_def_id: DefId, +} + +/////////////////////////////////////////////////////////////////////////// + +#[derive(Default)] +pub(crate) struct HirPlaceholderCollector(pub(crate) Vec<Span>); + +impl<'v> Visitor<'v> for HirPlaceholderCollector { + fn visit_ty(&mut self, t: &'v hir::Ty<'v>) { + if let hir::TyKind::Infer = t.kind { + self.0.push(t.span); + } + intravisit::walk_ty(self, t) + } + fn visit_generic_arg(&mut self, generic_arg: &'v hir::GenericArg<'v>) { + match generic_arg { + hir::GenericArg::Infer(inf) => { + self.0.push(inf.span); + intravisit::walk_inf(self, inf); + } + hir::GenericArg::Type(t) => self.visit_ty(t), + _ => {} + } + } + fn visit_array_length(&mut self, length: &'v hir::ArrayLen) { + if let &hir::ArrayLen::Infer(_, span) = length { + self.0.push(span); + } + intravisit::walk_array_len(self, length) + } +} + +struct CollectItemTypesVisitor<'tcx> { + tcx: TyCtxt<'tcx>, +} + +/// If there are any placeholder types (`_`), emit an error explaining that this is not allowed +/// and suggest adding type parameters in the appropriate place, taking into consideration any and +/// all already existing generic type parameters to avoid suggesting a name that is already in use. +pub(crate) fn placeholder_type_error<'tcx>( + tcx: TyCtxt<'tcx>, + generics: Option<&hir::Generics<'_>>, + placeholder_types: Vec<Span>, + suggest: bool, + hir_ty: Option<&hir::Ty<'_>>, + kind: &'static str, +) { + if placeholder_types.is_empty() { + return; + } + + placeholder_type_error_diag(tcx, generics, placeholder_types, vec![], suggest, hir_ty, kind) + .emit(); +} + +pub(crate) fn placeholder_type_error_diag<'tcx>( + tcx: TyCtxt<'tcx>, + generics: Option<&hir::Generics<'_>>, + placeholder_types: Vec<Span>, + additional_spans: Vec<Span>, + suggest: bool, + hir_ty: Option<&hir::Ty<'_>>, + kind: &'static str, +) -> DiagnosticBuilder<'tcx, ErrorGuaranteed> { + if placeholder_types.is_empty() { + return bad_placeholder(tcx, additional_spans, kind); + } + + let params = generics.map(|g| g.params).unwrap_or_default(); + let type_name = params.next_type_param_name(None); + let mut sugg: Vec<_> = + placeholder_types.iter().map(|sp| (*sp, (*type_name).to_string())).collect(); + + if let Some(generics) = generics { + if let Some(arg) = params.iter().find(|arg| { + matches!(arg.name, hir::ParamName::Plain(Ident { name: kw::Underscore, .. })) + }) { + // Account for `_` already present in cases like `struct S<_>(_);` and suggest + // `struct S<T>(T);` instead of `struct S<_, T>(T);`. + sugg.push((arg.span, (*type_name).to_string())); + } else if let Some(span) = generics.span_for_param_suggestion() { + // Account for bounds, we want `fn foo<T: E, K>(_: K)` not `fn foo<T, K: E>(_: K)`. + sugg.push((span, format!(", {}", type_name))); + } else { + sugg.push((generics.span, format!("<{}>", type_name))); + } + } + + let mut err = + bad_placeholder(tcx, placeholder_types.into_iter().chain(additional_spans).collect(), kind); + + // Suggest, but only if it is not a function in const or static + if suggest { + let mut is_fn = false; + let mut is_const_or_static = false; + + if let Some(hir_ty) = hir_ty && let hir::TyKind::BareFn(_) = hir_ty.kind { + is_fn = true; + + // Check if parent is const or static + let parent_id = tcx.hir().get_parent_node(hir_ty.hir_id); + let parent_node = tcx.hir().get(parent_id); + + is_const_or_static = matches!( + parent_node, + Node::Item(&hir::Item { + kind: hir::ItemKind::Const(..) | hir::ItemKind::Static(..), + .. + }) | Node::TraitItem(&hir::TraitItem { + kind: hir::TraitItemKind::Const(..), + .. + }) | Node::ImplItem(&hir::ImplItem { kind: hir::ImplItemKind::Const(..), .. }) + ); + } + + // if function is wrapped around a const or static, + // then don't show the suggestion + if !(is_fn && is_const_or_static) { + err.multipart_suggestion( + "use type parameters instead", + sugg, + Applicability::HasPlaceholders, + ); + } + } + + err +} + +fn reject_placeholder_type_signatures_in_item<'tcx>( + tcx: TyCtxt<'tcx>, + item: &'tcx hir::Item<'tcx>, +) { + let (generics, suggest) = match &item.kind { + hir::ItemKind::Union(_, generics) + | hir::ItemKind::Enum(_, generics) + | hir::ItemKind::TraitAlias(generics, _) + | hir::ItemKind::Trait(_, _, generics, ..) + | hir::ItemKind::Impl(hir::Impl { generics, .. }) + | hir::ItemKind::Struct(_, generics) => (generics, true), + hir::ItemKind::OpaqueTy(hir::OpaqueTy { generics, .. }) + | hir::ItemKind::TyAlias(_, generics) => (generics, false), + // `static`, `fn` and `const` are handled elsewhere to suggest appropriate type. + _ => return, + }; + + let mut visitor = HirPlaceholderCollector::default(); + visitor.visit_item(item); + + placeholder_type_error(tcx, Some(generics), visitor.0, suggest, None, item.kind.descr()); +} + +impl<'tcx> Visitor<'tcx> for CollectItemTypesVisitor<'tcx> { + type NestedFilter = nested_filter::OnlyBodies; + + fn nested_visit_map(&mut self) -> Self::Map { + self.tcx.hir() + } + + fn visit_item(&mut self, item: &'tcx hir::Item<'tcx>) { + convert_item(self.tcx, item.item_id()); + reject_placeholder_type_signatures_in_item(self.tcx, item); + intravisit::walk_item(self, item); + } + + fn visit_generics(&mut self, generics: &'tcx hir::Generics<'tcx>) { + for param in generics.params { + match param.kind { + hir::GenericParamKind::Lifetime { .. } => {} + hir::GenericParamKind::Type { default: Some(_), .. } => { + let def_id = self.tcx.hir().local_def_id(param.hir_id); + self.tcx.ensure().type_of(def_id); + } + hir::GenericParamKind::Type { .. } => {} + hir::GenericParamKind::Const { default, .. } => { + let def_id = self.tcx.hir().local_def_id(param.hir_id); + self.tcx.ensure().type_of(def_id); + if let Some(default) = default { + let default_def_id = self.tcx.hir().local_def_id(default.hir_id); + // need to store default and type of default + self.tcx.ensure().type_of(default_def_id); + self.tcx.ensure().const_param_default(def_id); + } + } + } + } + intravisit::walk_generics(self, generics); + } + + fn visit_expr(&mut self, expr: &'tcx hir::Expr<'tcx>) { + if let hir::ExprKind::Closure { .. } = expr.kind { + let def_id = self.tcx.hir().local_def_id(expr.hir_id); + self.tcx.ensure().generics_of(def_id); + // We do not call `type_of` for closures here as that + // depends on typecheck and would therefore hide + // any further errors in case one typeck fails. + } + intravisit::walk_expr(self, expr); + } + + fn visit_trait_item(&mut self, trait_item: &'tcx hir::TraitItem<'tcx>) { + convert_trait_item(self.tcx, trait_item.trait_item_id()); + intravisit::walk_trait_item(self, trait_item); + } + + fn visit_impl_item(&mut self, impl_item: &'tcx hir::ImplItem<'tcx>) { + convert_impl_item(self.tcx, impl_item.impl_item_id()); + intravisit::walk_impl_item(self, impl_item); + } +} + +/////////////////////////////////////////////////////////////////////////// +// Utility types and common code for the above passes. + +fn bad_placeholder<'tcx>( + tcx: TyCtxt<'tcx>, + mut spans: Vec<Span>, + kind: &'static str, +) -> DiagnosticBuilder<'tcx, ErrorGuaranteed> { + let kind = if kind.ends_with('s') { format!("{}es", kind) } else { format!("{}s", kind) }; + + spans.sort(); + let mut err = struct_span_err!( + tcx.sess, + spans.clone(), + E0121, + "the placeholder `_` is not allowed within types on item signatures for {}", + kind + ); + for span in spans { + err.span_label(span, "not allowed in type signatures"); + } + err +} + +impl<'tcx> ItemCtxt<'tcx> { + pub fn new(tcx: TyCtxt<'tcx>, item_def_id: DefId) -> ItemCtxt<'tcx> { + ItemCtxt { tcx, item_def_id } + } + + pub fn to_ty(&self, ast_ty: &hir::Ty<'_>) -> Ty<'tcx> { + <dyn AstConv<'_>>::ast_ty_to_ty(self, ast_ty) + } + + pub fn hir_id(&self) -> hir::HirId { + self.tcx.hir().local_def_id_to_hir_id(self.item_def_id.expect_local()) + } + + pub fn node(&self) -> hir::Node<'tcx> { + self.tcx.hir().get(self.hir_id()) + } +} + +impl<'tcx> AstConv<'tcx> for ItemCtxt<'tcx> { + fn tcx(&self) -> TyCtxt<'tcx> { + self.tcx + } + + fn item_def_id(&self) -> Option<DefId> { + Some(self.item_def_id) + } + + fn get_type_parameter_bounds( + &self, + span: Span, + def_id: DefId, + assoc_name: Ident, + ) -> ty::GenericPredicates<'tcx> { + self.tcx.at(span).type_param_predicates(( + self.item_def_id, + def_id.expect_local(), + assoc_name, + )) + } + + fn re_infer(&self, _: Option<&ty::GenericParamDef>, _: Span) -> Option<ty::Region<'tcx>> { + None + } + + fn allow_ty_infer(&self) -> bool { + false + } + + fn ty_infer(&self, _: Option<&ty::GenericParamDef>, span: Span) -> Ty<'tcx> { + self.tcx().ty_error_with_message(span, "bad placeholder type") + } + + fn ct_infer(&self, ty: Ty<'tcx>, _: Option<&ty::GenericParamDef>, span: Span) -> Const<'tcx> { + let ty = self.tcx.fold_regions(ty, |r, _| match *r { + ty::ReErased => self.tcx.lifetimes.re_static, + _ => r, + }); + self.tcx().const_error_with_message(ty, span, "bad placeholder constant") + } + + fn projected_ty_from_poly_trait_ref( + &self, + span: Span, + item_def_id: DefId, + item_segment: &hir::PathSegment<'_>, + poly_trait_ref: ty::PolyTraitRef<'tcx>, + ) -> Ty<'tcx> { + if let Some(trait_ref) = poly_trait_ref.no_bound_vars() { + let item_substs = <dyn AstConv<'tcx>>::create_substs_for_associated_item( + self, + span, + item_def_id, + item_segment, + trait_ref.substs, + ); + self.tcx().mk_projection(item_def_id, item_substs) + } else { + // There are no late-bound regions; we can just ignore the binder. + let mut err = struct_span_err!( + self.tcx().sess, + span, + E0212, + "cannot use the associated type of a trait \ + with uninferred generic parameters" + ); + + match self.node() { + hir::Node::Field(_) | hir::Node::Ctor(_) | hir::Node::Variant(_) => { + let item = self + .tcx + .hir() + .expect_item(self.tcx.hir().get_parent_item(self.hir_id()).def_id); + match &item.kind { + hir::ItemKind::Enum(_, generics) + | hir::ItemKind::Struct(_, generics) + | hir::ItemKind::Union(_, generics) => { + let lt_name = get_new_lifetime_name(self.tcx, poly_trait_ref, generics); + let (lt_sp, sugg) = match generics.params { + [] => (generics.span, format!("<{}>", lt_name)), + [bound, ..] => { + (bound.span.shrink_to_lo(), format!("{}, ", lt_name)) + } + }; + let suggestions = vec![ + (lt_sp, sugg), + ( + span.with_hi(item_segment.ident.span.lo()), + format!( + "{}::", + // Replace the existing lifetimes with a new named lifetime. + self.tcx.replace_late_bound_regions_uncached( + poly_trait_ref, + |_| { + self.tcx.mk_region(ty::ReEarlyBound( + ty::EarlyBoundRegion { + def_id: item_def_id, + index: 0, + name: Symbol::intern(<_name), + }, + )) + } + ), + ), + ), + ]; + err.multipart_suggestion( + "use a fully qualified path with explicit lifetimes", + suggestions, + Applicability::MaybeIncorrect, + ); + } + _ => {} + } + } + hir::Node::Item(hir::Item { + kind: + hir::ItemKind::Struct(..) | hir::ItemKind::Enum(..) | hir::ItemKind::Union(..), + .. + }) => {} + hir::Node::Item(_) + | hir::Node::ForeignItem(_) + | hir::Node::TraitItem(_) + | hir::Node::ImplItem(_) => { + err.span_suggestion_verbose( + span.with_hi(item_segment.ident.span.lo()), + "use a fully qualified path with inferred lifetimes", + format!( + "{}::", + // Erase named lt, we want `<A as B<'_>::C`, not `<A as B<'a>::C`. + self.tcx.anonymize_late_bound_regions(poly_trait_ref).skip_binder(), + ), + Applicability::MaybeIncorrect, + ); + } + _ => {} + } + err.emit(); + self.tcx().ty_error() + } + } + + fn normalize_ty(&self, _span: Span, ty: Ty<'tcx>) -> Ty<'tcx> { + // Types in item signatures are not normalized to avoid undue dependencies. + ty + } + + fn set_tainted_by_errors(&self) { + // There's no obvious place to track this, so just let it go. + } + + fn record_ty(&self, _hir_id: hir::HirId, _ty: Ty<'tcx>, _span: Span) { + // There's no place to record types from signatures? + } +} + +/// Synthesize a new lifetime name that doesn't clash with any of the lifetimes already present. +fn get_new_lifetime_name<'tcx>( + tcx: TyCtxt<'tcx>, + poly_trait_ref: ty::PolyTraitRef<'tcx>, + generics: &hir::Generics<'tcx>, +) -> String { + let existing_lifetimes = tcx + .collect_referenced_late_bound_regions(&poly_trait_ref) + .into_iter() + .filter_map(|lt| { + if let ty::BoundRegionKind::BrNamed(_, name) = lt { + Some(name.as_str().to_string()) + } else { + None + } + }) + .chain(generics.params.iter().filter_map(|param| { + if let hir::GenericParamKind::Lifetime { .. } = ¶m.kind { + Some(param.name.ident().as_str().to_string()) + } else { + None + } + })) + .collect::<FxHashSet<String>>(); + + let a_to_z_repeat_n = |n| { + (b'a'..=b'z').map(move |c| { + let mut s = '\''.to_string(); + s.extend(std::iter::repeat(char::from(c)).take(n)); + s + }) + }; + + // If all single char lifetime names are present, we wrap around and double the chars. + (1..).flat_map(a_to_z_repeat_n).find(|lt| !existing_lifetimes.contains(lt.as_str())).unwrap() +} + +/// Returns the predicates defined on `item_def_id` of the form +/// `X: Foo` where `X` is the type parameter `def_id`. +#[instrument(level = "trace", skip(tcx))] +fn type_param_predicates( + tcx: TyCtxt<'_>, + (item_def_id, def_id, assoc_name): (DefId, LocalDefId, Ident), +) -> ty::GenericPredicates<'_> { + use rustc_hir::*; + + // In the AST, bounds can derive from two places. Either + // written inline like `<T: Foo>` or in a where-clause like + // `where T: Foo`. + + let param_id = tcx.hir().local_def_id_to_hir_id(def_id); + let param_owner = tcx.hir().ty_param_owner(def_id); + let generics = tcx.generics_of(param_owner); + let index = generics.param_def_id_to_index[&def_id.to_def_id()]; + let ty = tcx.mk_ty_param(index, tcx.hir().ty_param_name(def_id)); + + // Don't look for bounds where the type parameter isn't in scope. + let parent = if item_def_id == param_owner.to_def_id() { + None + } else { + tcx.generics_of(item_def_id).parent + }; + + let mut result = parent + .map(|parent| { + let icx = ItemCtxt::new(tcx, parent); + icx.get_type_parameter_bounds(DUMMY_SP, def_id.to_def_id(), assoc_name) + }) + .unwrap_or_default(); + let mut extend = None; + + let item_hir_id = tcx.hir().local_def_id_to_hir_id(item_def_id.expect_local()); + let ast_generics = match tcx.hir().get(item_hir_id) { + Node::TraitItem(item) => &item.generics, + + Node::ImplItem(item) => &item.generics, + + Node::Item(item) => { + match item.kind { + ItemKind::Fn(.., ref generics, _) + | ItemKind::Impl(hir::Impl { ref generics, .. }) + | ItemKind::TyAlias(_, ref generics) + | ItemKind::OpaqueTy(OpaqueTy { + ref generics, + origin: hir::OpaqueTyOrigin::TyAlias, + .. + }) + | ItemKind::Enum(_, ref generics) + | ItemKind::Struct(_, ref generics) + | ItemKind::Union(_, ref generics) => generics, + ItemKind::Trait(_, _, ref generics, ..) => { + // Implied `Self: Trait` and supertrait bounds. + if param_id == item_hir_id { + let identity_trait_ref = ty::TraitRef::identity(tcx, item_def_id); + extend = + Some((identity_trait_ref.without_const().to_predicate(tcx), item.span)); + } + generics + } + _ => return result, + } + } + + Node::ForeignItem(item) => match item.kind { + ForeignItemKind::Fn(_, _, ref generics) => generics, + _ => return result, + }, + + _ => return result, + }; + + let icx = ItemCtxt::new(tcx, item_def_id); + let extra_predicates = extend.into_iter().chain( + icx.type_parameter_bounds_in_generics( + ast_generics, + param_id, + ty, + OnlySelfBounds(true), + Some(assoc_name), + ) + .into_iter() + .filter(|(predicate, _)| match predicate.kind().skip_binder() { + ty::PredicateKind::Trait(data) => data.self_ty().is_param(index), + _ => false, + }), + ); + result.predicates = + tcx.arena.alloc_from_iter(result.predicates.iter().copied().chain(extra_predicates)); + result +} + +impl<'tcx> ItemCtxt<'tcx> { + /// Finds bounds from `hir::Generics`. This requires scanning through the + /// AST. We do this to avoid having to convert *all* the bounds, which + /// would create artificial cycles. Instead, we can only convert the + /// bounds for a type parameter `X` if `X::Foo` is used. + #[instrument(level = "trace", skip(self, ast_generics))] + fn type_parameter_bounds_in_generics( + &self, + ast_generics: &'tcx hir::Generics<'tcx>, + param_id: hir::HirId, + ty: Ty<'tcx>, + only_self_bounds: OnlySelfBounds, + assoc_name: Option<Ident>, + ) -> Vec<(ty::Predicate<'tcx>, Span)> { + let param_def_id = self.tcx.hir().local_def_id(param_id).to_def_id(); + trace!(?param_def_id); + ast_generics + .predicates + .iter() + .filter_map(|wp| match *wp { + hir::WherePredicate::BoundPredicate(ref bp) => Some(bp), + _ => None, + }) + .flat_map(|bp| { + let bt = if bp.is_param_bound(param_def_id) { + Some(ty) + } else if !only_self_bounds.0 { + Some(self.to_ty(bp.bounded_ty)) + } else { + None + }; + let bvars = self.tcx.late_bound_vars(bp.bounded_ty.hir_id); + + bp.bounds.iter().filter_map(move |b| bt.map(|bt| (bt, b, bvars))).filter( + |(_, b, _)| match assoc_name { + Some(assoc_name) => self.bound_defines_assoc_item(b, assoc_name), + None => true, + }, + ) + }) + .flat_map(|(bt, b, bvars)| predicates_from_bound(self, bt, b, bvars)) + .collect() + } + + #[instrument(level = "trace", skip(self))] + fn bound_defines_assoc_item(&self, b: &hir::GenericBound<'_>, assoc_name: Ident) -> bool { + match b { + hir::GenericBound::Trait(poly_trait_ref, _) => { + let trait_ref = &poly_trait_ref.trait_ref; + if let Some(trait_did) = trait_ref.trait_def_id() { + self.tcx.trait_may_define_assoc_type(trait_did, assoc_name) + } else { + false + } + } + _ => false, + } + } +} + +fn convert_item(tcx: TyCtxt<'_>, item_id: hir::ItemId) { + let it = tcx.hir().item(item_id); + debug!("convert: item {} with id {}", it.ident, it.hir_id()); + let def_id = item_id.def_id.def_id; + + match it.kind { + // These don't define types. + hir::ItemKind::ExternCrate(_) + | hir::ItemKind::Use(..) + | hir::ItemKind::Macro(..) + | hir::ItemKind::Mod(_) + | hir::ItemKind::GlobalAsm(_) => {} + hir::ItemKind::ForeignMod { items, .. } => { + for item in items { + let item = tcx.hir().foreign_item(item.id); + tcx.ensure().generics_of(item.def_id); + tcx.ensure().type_of(item.def_id); + tcx.ensure().predicates_of(item.def_id); + match item.kind { + hir::ForeignItemKind::Fn(..) => tcx.ensure().fn_sig(item.def_id), + hir::ForeignItemKind::Static(..) => { + let mut visitor = HirPlaceholderCollector::default(); + visitor.visit_foreign_item(item); + placeholder_type_error( + tcx, + None, + visitor.0, + false, + None, + "static variable", + ); + } + _ => (), + } + } + } + hir::ItemKind::Enum(ref enum_definition, _) => { + tcx.ensure().generics_of(def_id); + tcx.ensure().type_of(def_id); + tcx.ensure().predicates_of(def_id); + convert_enum_variant_types(tcx, def_id.to_def_id(), enum_definition.variants); + } + hir::ItemKind::Impl { .. } => { + tcx.ensure().generics_of(def_id); + tcx.ensure().type_of(def_id); + tcx.ensure().impl_trait_ref(def_id); + tcx.ensure().predicates_of(def_id); + } + hir::ItemKind::Trait(..) => { + tcx.ensure().generics_of(def_id); + tcx.ensure().trait_def(def_id); + tcx.at(it.span).super_predicates_of(def_id); + tcx.ensure().predicates_of(def_id); + } + hir::ItemKind::TraitAlias(..) => { + tcx.ensure().generics_of(def_id); + tcx.at(it.span).super_predicates_of(def_id); + tcx.ensure().predicates_of(def_id); + } + hir::ItemKind::Struct(ref struct_def, _) | hir::ItemKind::Union(ref struct_def, _) => { + tcx.ensure().generics_of(def_id); + tcx.ensure().type_of(def_id); + tcx.ensure().predicates_of(def_id); + + for f in struct_def.fields() { + let def_id = tcx.hir().local_def_id(f.hir_id); + tcx.ensure().generics_of(def_id); + tcx.ensure().type_of(def_id); + tcx.ensure().predicates_of(def_id); + } + + if let Some(ctor_hir_id) = struct_def.ctor_hir_id() { + convert_variant_ctor(tcx, ctor_hir_id); + } + } + + // Desugared from `impl Trait`, so visited by the function's return type. + hir::ItemKind::OpaqueTy(hir::OpaqueTy { + origin: hir::OpaqueTyOrigin::FnReturn(..) | hir::OpaqueTyOrigin::AsyncFn(..), + .. + }) => {} + + // Don't call `type_of` on opaque types, since that depends on type + // checking function bodies. `check_item_type` ensures that it's called + // instead. + hir::ItemKind::OpaqueTy(..) => { + tcx.ensure().generics_of(def_id); + tcx.ensure().predicates_of(def_id); + tcx.ensure().explicit_item_bounds(def_id); + } + hir::ItemKind::TyAlias(..) + | hir::ItemKind::Static(..) + | hir::ItemKind::Const(..) + | hir::ItemKind::Fn(..) => { + tcx.ensure().generics_of(def_id); + tcx.ensure().type_of(def_id); + tcx.ensure().predicates_of(def_id); + match it.kind { + hir::ItemKind::Fn(..) => tcx.ensure().fn_sig(def_id), + hir::ItemKind::OpaqueTy(..) => tcx.ensure().item_bounds(def_id), + hir::ItemKind::Const(ty, ..) | hir::ItemKind::Static(ty, ..) => { + if !is_suggestable_infer_ty(ty) { + let mut visitor = HirPlaceholderCollector::default(); + visitor.visit_item(it); + placeholder_type_error(tcx, None, visitor.0, false, None, it.kind.descr()); + } + } + _ => (), + } + } + } +} + +fn convert_trait_item(tcx: TyCtxt<'_>, trait_item_id: hir::TraitItemId) { + let trait_item = tcx.hir().trait_item(trait_item_id); + let def_id = trait_item_id.def_id; + tcx.ensure().generics_of(def_id); + + match trait_item.kind { + hir::TraitItemKind::Fn(..) => { + tcx.ensure().type_of(def_id); + tcx.ensure().fn_sig(def_id); + } + + hir::TraitItemKind::Const(.., Some(_)) => { + tcx.ensure().type_of(def_id); + } + + hir::TraitItemKind::Const(hir_ty, _) => { + tcx.ensure().type_of(def_id); + // Account for `const C: _;`. + let mut visitor = HirPlaceholderCollector::default(); + visitor.visit_trait_item(trait_item); + if !tcx.sess.diagnostic().has_stashed_diagnostic(hir_ty.span, StashKey::ItemNoType) { + placeholder_type_error(tcx, None, visitor.0, false, None, "constant"); + } + } + + hir::TraitItemKind::Type(_, Some(_)) => { + tcx.ensure().item_bounds(def_id); + tcx.ensure().type_of(def_id); + // Account for `type T = _;`. + let mut visitor = HirPlaceholderCollector::default(); + visitor.visit_trait_item(trait_item); + placeholder_type_error(tcx, None, visitor.0, false, None, "associated type"); + } + + hir::TraitItemKind::Type(_, None) => { + tcx.ensure().item_bounds(def_id); + // #74612: Visit and try to find bad placeholders + // even if there is no concrete type. + let mut visitor = HirPlaceholderCollector::default(); + visitor.visit_trait_item(trait_item); + + placeholder_type_error(tcx, None, visitor.0, false, None, "associated type"); + } + }; + + tcx.ensure().predicates_of(def_id); +} + +fn convert_impl_item(tcx: TyCtxt<'_>, impl_item_id: hir::ImplItemId) { + let def_id = impl_item_id.def_id; + tcx.ensure().generics_of(def_id); + tcx.ensure().type_of(def_id); + tcx.ensure().predicates_of(def_id); + let impl_item = tcx.hir().impl_item(impl_item_id); + match impl_item.kind { + hir::ImplItemKind::Fn(..) => { + tcx.ensure().fn_sig(def_id); + } + hir::ImplItemKind::TyAlias(_) => { + // Account for `type T = _;` + let mut visitor = HirPlaceholderCollector::default(); + visitor.visit_impl_item(impl_item); + + placeholder_type_error(tcx, None, visitor.0, false, None, "associated type"); + } + hir::ImplItemKind::Const(..) => {} + } +} + +fn convert_variant_ctor(tcx: TyCtxt<'_>, ctor_id: hir::HirId) { + let def_id = tcx.hir().local_def_id(ctor_id); + tcx.ensure().generics_of(def_id); + tcx.ensure().type_of(def_id); + tcx.ensure().predicates_of(def_id); +} + +fn convert_enum_variant_types(tcx: TyCtxt<'_>, def_id: DefId, variants: &[hir::Variant<'_>]) { + let def = tcx.adt_def(def_id); + let repr_type = def.repr().discr_type(); + let initial = repr_type.initial_discriminant(tcx); + let mut prev_discr = None::<Discr<'_>>; + + // fill the discriminant values and field types + for variant in variants { + let wrapped_discr = prev_discr.map_or(initial, |d| d.wrap_incr(tcx)); + prev_discr = Some( + if let Some(ref e) = variant.disr_expr { + let expr_did = tcx.hir().local_def_id(e.hir_id); + def.eval_explicit_discr(tcx, expr_did.to_def_id()) + } else if let Some(discr) = repr_type.disr_incr(tcx, prev_discr) { + Some(discr) + } else { + struct_span_err!(tcx.sess, variant.span, E0370, "enum discriminant overflowed") + .span_label( + variant.span, + format!("overflowed on value after {}", prev_discr.unwrap()), + ) + .note(&format!( + "explicitly set `{} = {}` if that is desired outcome", + variant.ident, wrapped_discr + )) + .emit(); + None + } + .unwrap_or(wrapped_discr), + ); + + for f in variant.data.fields() { + let def_id = tcx.hir().local_def_id(f.hir_id); + tcx.ensure().generics_of(def_id); + tcx.ensure().type_of(def_id); + tcx.ensure().predicates_of(def_id); + } + + // Convert the ctor, if any. This also registers the variant as + // an item. + if let Some(ctor_hir_id) = variant.data.ctor_hir_id() { + convert_variant_ctor(tcx, ctor_hir_id); + } + } +} + +fn convert_variant( + tcx: TyCtxt<'_>, + variant_did: Option<LocalDefId>, + ctor_did: Option<LocalDefId>, + ident: Ident, + discr: ty::VariantDiscr, + def: &hir::VariantData<'_>, + adt_kind: ty::AdtKind, + parent_did: LocalDefId, +) -> ty::VariantDef { + let mut seen_fields: FxHashMap<Ident, Span> = Default::default(); + let fields = def + .fields() + .iter() + .map(|f| { + let fid = tcx.hir().local_def_id(f.hir_id); + let dup_span = seen_fields.get(&f.ident.normalize_to_macros_2_0()).cloned(); + if let Some(prev_span) = dup_span { + tcx.sess.emit_err(errors::FieldAlreadyDeclared { + field_name: f.ident, + span: f.span, + prev_span, + }); + } else { + seen_fields.insert(f.ident.normalize_to_macros_2_0(), f.span); + } + + ty::FieldDef { did: fid.to_def_id(), name: f.ident.name, vis: tcx.visibility(fid) } + }) + .collect(); + let recovered = match def { + hir::VariantData::Struct(_, r) => *r, + _ => false, + }; + ty::VariantDef::new( + ident.name, + variant_did.map(LocalDefId::to_def_id), + ctor_did.map(LocalDefId::to_def_id), + discr, + fields, + CtorKind::from_hir(def), + adt_kind, + parent_did.to_def_id(), + recovered, + adt_kind == AdtKind::Struct && tcx.has_attr(parent_did.to_def_id(), sym::non_exhaustive) + || variant_did.map_or(false, |variant_did| { + tcx.has_attr(variant_did.to_def_id(), sym::non_exhaustive) + }), + ) +} + +fn adt_def<'tcx>(tcx: TyCtxt<'tcx>, def_id: DefId) -> ty::AdtDef<'tcx> { + use rustc_hir::*; + + let def_id = def_id.expect_local(); + let hir_id = tcx.hir().local_def_id_to_hir_id(def_id); + let Node::Item(item) = tcx.hir().get(hir_id) else { + bug!(); + }; + + let repr = ReprOptions::new(tcx, def_id.to_def_id()); + let (kind, variants) = match item.kind { + ItemKind::Enum(ref def, _) => { + let mut distance_from_explicit = 0; + let variants = def + .variants + .iter() + .map(|v| { + let variant_did = Some(tcx.hir().local_def_id(v.id)); + let ctor_did = + v.data.ctor_hir_id().map(|hir_id| tcx.hir().local_def_id(hir_id)); + + let discr = if let Some(ref e) = v.disr_expr { + distance_from_explicit = 0; + ty::VariantDiscr::Explicit(tcx.hir().local_def_id(e.hir_id).to_def_id()) + } else { + ty::VariantDiscr::Relative(distance_from_explicit) + }; + distance_from_explicit += 1; + + convert_variant( + tcx, + variant_did, + ctor_did, + v.ident, + discr, + &v.data, + AdtKind::Enum, + def_id, + ) + }) + .collect(); + + (AdtKind::Enum, variants) + } + ItemKind::Struct(ref def, _) => { + let variant_did = None::<LocalDefId>; + let ctor_did = def.ctor_hir_id().map(|hir_id| tcx.hir().local_def_id(hir_id)); + + let variants = std::iter::once(convert_variant( + tcx, + variant_did, + ctor_did, + item.ident, + ty::VariantDiscr::Relative(0), + def, + AdtKind::Struct, + def_id, + )) + .collect(); + + (AdtKind::Struct, variants) + } + ItemKind::Union(ref def, _) => { + let variant_did = None; + let ctor_did = def.ctor_hir_id().map(|hir_id| tcx.hir().local_def_id(hir_id)); + + let variants = std::iter::once(convert_variant( + tcx, + variant_did, + ctor_did, + item.ident, + ty::VariantDiscr::Relative(0), + def, + AdtKind::Union, + def_id, + )) + .collect(); + + (AdtKind::Union, variants) + } + _ => bug!(), + }; + tcx.alloc_adt_def(def_id.to_def_id(), kind, variants, repr) +} + +/// Ensures that the super-predicates of the trait with a `DefId` +/// of `trait_def_id` are converted and stored. This also ensures that +/// the transitive super-predicates are converted. +fn super_predicates_of(tcx: TyCtxt<'_>, trait_def_id: DefId) -> ty::GenericPredicates<'_> { + debug!("super_predicates(trait_def_id={:?})", trait_def_id); + tcx.super_predicates_that_define_assoc_type((trait_def_id, None)) +} + +/// Ensures that the super-predicates of the trait with a `DefId` +/// of `trait_def_id` are converted and stored. This also ensures that +/// the transitive super-predicates are converted. +fn super_predicates_that_define_assoc_type( + tcx: TyCtxt<'_>, + (trait_def_id, assoc_name): (DefId, Option<Ident>), +) -> ty::GenericPredicates<'_> { + debug!( + "super_predicates_that_define_assoc_type(trait_def_id={:?}, assoc_name={:?})", + trait_def_id, assoc_name + ); + if trait_def_id.is_local() { + debug!("super_predicates_that_define_assoc_type: local trait_def_id={:?}", trait_def_id); + let trait_hir_id = tcx.hir().local_def_id_to_hir_id(trait_def_id.expect_local()); + + let Node::Item(item) = tcx.hir().get(trait_hir_id) else { + bug!("trait_node_id {} is not an item", trait_hir_id); + }; + + let (generics, bounds) = match item.kind { + hir::ItemKind::Trait(.., ref generics, ref supertraits, _) => (generics, supertraits), + hir::ItemKind::TraitAlias(ref generics, ref supertraits) => (generics, supertraits), + _ => span_bug!(item.span, "super_predicates invoked on non-trait"), + }; + + let icx = ItemCtxt::new(tcx, trait_def_id); + + // Convert the bounds that follow the colon, e.g., `Bar + Zed` in `trait Foo: Bar + Zed`. + let self_param_ty = tcx.types.self_param; + let superbounds1 = if let Some(assoc_name) = assoc_name { + <dyn AstConv<'_>>::compute_bounds_that_match_assoc_type( + &icx, + self_param_ty, + bounds, + assoc_name, + ) + } else { + <dyn AstConv<'_>>::compute_bounds(&icx, self_param_ty, bounds) + }; + + let superbounds1 = superbounds1.predicates(tcx, self_param_ty); + + // Convert any explicit superbounds in the where-clause, + // e.g., `trait Foo where Self: Bar`. + // In the case of trait aliases, however, we include all bounds in the where-clause, + // so e.g., `trait Foo = where u32: PartialEq<Self>` would include `u32: PartialEq<Self>` + // as one of its "superpredicates". + let is_trait_alias = tcx.is_trait_alias(trait_def_id); + let superbounds2 = icx.type_parameter_bounds_in_generics( + generics, + item.hir_id(), + self_param_ty, + OnlySelfBounds(!is_trait_alias), + assoc_name, + ); + + // Combine the two lists to form the complete set of superbounds: + let superbounds = &*tcx.arena.alloc_from_iter(superbounds1.into_iter().chain(superbounds2)); + debug!(?superbounds); + + // Now require that immediate supertraits are converted, + // which will, in turn, reach indirect supertraits. + if assoc_name.is_none() { + // Now require that immediate supertraits are converted, + // which will, in turn, reach indirect supertraits. + for &(pred, span) in superbounds { + debug!("superbound: {:?}", pred); + if let ty::PredicateKind::Trait(bound) = pred.kind().skip_binder() { + tcx.at(span).super_predicates_of(bound.def_id()); + } + } + } + + ty::GenericPredicates { parent: None, predicates: superbounds } + } else { + // if `assoc_name` is None, then the query should've been redirected to an + // external provider + assert!(assoc_name.is_some()); + tcx.super_predicates_of(trait_def_id) + } +} + +fn trait_def(tcx: TyCtxt<'_>, def_id: DefId) -> ty::TraitDef { + let item = tcx.hir().expect_item(def_id.expect_local()); + + let (is_auto, unsafety, items) = match item.kind { + hir::ItemKind::Trait(is_auto, unsafety, .., items) => { + (is_auto == hir::IsAuto::Yes, unsafety, items) + } + hir::ItemKind::TraitAlias(..) => (false, hir::Unsafety::Normal, &[][..]), + _ => span_bug!(item.span, "trait_def_of_item invoked on non-trait"), + }; + + let paren_sugar = tcx.has_attr(def_id, sym::rustc_paren_sugar); + if paren_sugar && !tcx.features().unboxed_closures { + tcx.sess + .struct_span_err( + item.span, + "the `#[rustc_paren_sugar]` attribute is a temporary means of controlling \ + which traits can use parenthetical notation", + ) + .help("add `#![feature(unboxed_closures)]` to the crate attributes to use it") + .emit(); + } + + let is_marker = tcx.has_attr(def_id, sym::marker); + let skip_array_during_method_dispatch = + tcx.has_attr(def_id, sym::rustc_skip_array_during_method_dispatch); + let spec_kind = if tcx.has_attr(def_id, sym::rustc_unsafe_specialization_marker) { + ty::trait_def::TraitSpecializationKind::Marker + } else if tcx.has_attr(def_id, sym::rustc_specialization_trait) { + ty::trait_def::TraitSpecializationKind::AlwaysApplicable + } else { + ty::trait_def::TraitSpecializationKind::None + }; + let must_implement_one_of = tcx + .get_attr(def_id, sym::rustc_must_implement_one_of) + // Check that there are at least 2 arguments of `#[rustc_must_implement_one_of]` + // and that they are all identifiers + .and_then(|attr| match attr.meta_item_list() { + Some(items) if items.len() < 2 => { + tcx.sess + .struct_span_err( + attr.span, + "the `#[rustc_must_implement_one_of]` attribute must be \ + used with at least 2 args", + ) + .emit(); + + None + } + Some(items) => items + .into_iter() + .map(|item| item.ident().ok_or(item.span())) + .collect::<Result<Box<[_]>, _>>() + .map_err(|span| { + tcx.sess + .struct_span_err(span, "must be a name of an associated function") + .emit(); + }) + .ok() + .zip(Some(attr.span)), + // Error is reported by `rustc_attr!` + None => None, + }) + // Check that all arguments of `#[rustc_must_implement_one_of]` reference + // functions in the trait with default implementations + .and_then(|(list, attr_span)| { + let errors = list.iter().filter_map(|ident| { + let item = items.iter().find(|item| item.ident == *ident); + + match item { + Some(item) if matches!(item.kind, hir::AssocItemKind::Fn { .. }) => { + if !tcx.impl_defaultness(item.id.def_id).has_value() { + tcx.sess + .struct_span_err( + item.span, + "This function doesn't have a default implementation", + ) + .span_note(attr_span, "required by this annotation") + .emit(); + + return Some(()); + } + + return None; + } + Some(item) => { + tcx.sess + .struct_span_err(item.span, "Not a function") + .span_note(attr_span, "required by this annotation") + .note( + "All `#[rustc_must_implement_one_of]` arguments \ + must be associated function names", + ) + .emit(); + } + None => { + tcx.sess + .struct_span_err(ident.span, "Function not found in this trait") + .emit(); + } + } + + Some(()) + }); + + (errors.count() == 0).then_some(list) + }) + // Check for duplicates + .and_then(|list| { + let mut set: FxHashMap<Symbol, Span> = FxHashMap::default(); + let mut no_dups = true; + + for ident in &*list { + if let Some(dup) = set.insert(ident.name, ident.span) { + tcx.sess + .struct_span_err(vec![dup, ident.span], "Functions names are duplicated") + .note( + "All `#[rustc_must_implement_one_of]` arguments \ + must be unique", + ) + .emit(); + + no_dups = false; + } + } + + no_dups.then_some(list) + }); + + ty::TraitDef::new( + def_id, + unsafety, + paren_sugar, + is_auto, + is_marker, + skip_array_during_method_dispatch, + spec_kind, + must_implement_one_of, + ) +} + +fn has_late_bound_regions<'tcx>(tcx: TyCtxt<'tcx>, node: Node<'tcx>) -> Option<Span> { + struct LateBoundRegionsDetector<'tcx> { + tcx: TyCtxt<'tcx>, + outer_index: ty::DebruijnIndex, + has_late_bound_regions: Option<Span>, + } + + impl<'tcx> Visitor<'tcx> for LateBoundRegionsDetector<'tcx> { + fn visit_ty(&mut self, ty: &'tcx hir::Ty<'tcx>) { + if self.has_late_bound_regions.is_some() { + return; + } + match ty.kind { + hir::TyKind::BareFn(..) => { + self.outer_index.shift_in(1); + intravisit::walk_ty(self, ty); + self.outer_index.shift_out(1); + } + _ => intravisit::walk_ty(self, ty), + } + } + + fn visit_poly_trait_ref(&mut self, tr: &'tcx hir::PolyTraitRef<'tcx>) { + if self.has_late_bound_regions.is_some() { + return; + } + self.outer_index.shift_in(1); + intravisit::walk_poly_trait_ref(self, tr); + self.outer_index.shift_out(1); + } + + fn visit_lifetime(&mut self, lt: &'tcx hir::Lifetime) { + if self.has_late_bound_regions.is_some() { + return; + } + + match self.tcx.named_region(lt.hir_id) { + Some(rl::Region::Static | rl::Region::EarlyBound(..)) => {} + Some(rl::Region::LateBound(debruijn, _, _)) if debruijn < self.outer_index => {} + Some(rl::Region::LateBound(..) | rl::Region::Free(..)) | None => { + self.has_late_bound_regions = Some(lt.span); + } + } + } + } + + fn has_late_bound_regions<'tcx>( + tcx: TyCtxt<'tcx>, + generics: &'tcx hir::Generics<'tcx>, + decl: &'tcx hir::FnDecl<'tcx>, + ) -> Option<Span> { + let mut visitor = LateBoundRegionsDetector { + tcx, + outer_index: ty::INNERMOST, + has_late_bound_regions: None, + }; + for param in generics.params { + if let GenericParamKind::Lifetime { .. } = param.kind { + if tcx.is_late_bound(param.hir_id) { + return Some(param.span); + } + } + } + visitor.visit_fn_decl(decl); + visitor.has_late_bound_regions + } + + match node { + Node::TraitItem(item) => match item.kind { + hir::TraitItemKind::Fn(ref sig, _) => { + has_late_bound_regions(tcx, &item.generics, sig.decl) + } + _ => None, + }, + Node::ImplItem(item) => match item.kind { + hir::ImplItemKind::Fn(ref sig, _) => { + has_late_bound_regions(tcx, &item.generics, sig.decl) + } + _ => None, + }, + Node::ForeignItem(item) => match item.kind { + hir::ForeignItemKind::Fn(fn_decl, _, ref generics) => { + has_late_bound_regions(tcx, generics, fn_decl) + } + _ => None, + }, + Node::Item(item) => match item.kind { + hir::ItemKind::Fn(ref sig, .., ref generics, _) => { + has_late_bound_regions(tcx, generics, sig.decl) + } + _ => None, + }, + _ => None, + } +} + +struct AnonConstInParamTyDetector { + in_param_ty: bool, + found_anon_const_in_param_ty: bool, + ct: HirId, +} + +impl<'v> Visitor<'v> for AnonConstInParamTyDetector { + fn visit_generic_param(&mut self, p: &'v hir::GenericParam<'v>) { + if let GenericParamKind::Const { ty, default: _ } = p.kind { + let prev = self.in_param_ty; + self.in_param_ty = true; + self.visit_ty(ty); + self.in_param_ty = prev; + } + } + + fn visit_anon_const(&mut self, c: &'v hir::AnonConst) { + if self.in_param_ty && self.ct == c.hir_id { + self.found_anon_const_in_param_ty = true; + } else { + intravisit::walk_anon_const(self, c) + } + } +} + +fn generics_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::Generics { + use rustc_hir::*; + + let hir_id = tcx.hir().local_def_id_to_hir_id(def_id.expect_local()); + + let node = tcx.hir().get(hir_id); + let parent_def_id = match node { + Node::ImplItem(_) + | Node::TraitItem(_) + | Node::Variant(_) + | Node::Ctor(..) + | Node::Field(_) => { + let parent_id = tcx.hir().get_parent_item(hir_id); + Some(parent_id.to_def_id()) + } + // FIXME(#43408) always enable this once `lazy_normalization` is + // stable enough and does not need a feature gate anymore. + Node::AnonConst(_) => { + let parent_def_id = tcx.hir().get_parent_item(hir_id); + + let mut in_param_ty = false; + for (_parent, node) in tcx.hir().parent_iter(hir_id) { + if let Some(generics) = node.generics() { + let mut visitor = AnonConstInParamTyDetector { + in_param_ty: false, + found_anon_const_in_param_ty: false, + ct: hir_id, + }; + + visitor.visit_generics(generics); + in_param_ty = visitor.found_anon_const_in_param_ty; + break; + } + } + + if in_param_ty { + // We do not allow generic parameters in anon consts if we are inside + // of a const parameter type, e.g. `struct Foo<const N: usize, const M: [u8; N]>` is not allowed. + None + } else if tcx.lazy_normalization() { + if let Some(param_id) = tcx.hir().opt_const_param_default_param_hir_id(hir_id) { + // If the def_id we are calling generics_of on is an anon ct default i.e: + // + // struct Foo<const N: usize = { .. }>; + // ^^^ ^ ^^^^^^ def id of this anon const + // ^ ^ param_id + // ^ parent_def_id + // + // then we only want to return generics for params to the left of `N`. If we don't do that we + // end up with that const looking like: `ty::ConstKind::Unevaluated(def_id, substs: [N#0])`. + // + // This causes ICEs (#86580) when building the substs for Foo in `fn foo() -> Foo { .. }` as + // we substitute the defaults with the partially built substs when we build the substs. Subst'ing + // the `N#0` on the unevaluated const indexes into the empty substs we're in the process of building. + // + // We fix this by having this function return the parent's generics ourselves and truncating the + // generics to only include non-forward declared params (with the exception of the `Self` ty) + // + // For the above code example that means we want `substs: []` + // For the following struct def we want `substs: [N#0]` when generics_of is called on + // the def id of the `{ N + 1 }` anon const + // struct Foo<const N: usize, const M: usize = { N + 1 }>; + // + // This has some implications for how we get the predicates available to the anon const + // see `explicit_predicates_of` for more information on this + let generics = tcx.generics_of(parent_def_id.to_def_id()); + let param_def = tcx.hir().local_def_id(param_id).to_def_id(); + let param_def_idx = generics.param_def_id_to_index[¶m_def]; + // In the above example this would be .params[..N#0] + let params = generics.params[..param_def_idx as usize].to_owned(); + let param_def_id_to_index = + params.iter().map(|param| (param.def_id, param.index)).collect(); + + return ty::Generics { + // we set the parent of these generics to be our parent's parent so that we + // dont end up with substs: [N, M, N] for the const default on a struct like this: + // struct Foo<const N: usize, const M: usize = { ... }>; + parent: generics.parent, + parent_count: generics.parent_count, + params, + param_def_id_to_index, + has_self: generics.has_self, + has_late_bound_regions: generics.has_late_bound_regions, + }; + } + + // HACK(eddyb) this provides the correct generics when + // `feature(generic_const_expressions)` is enabled, so that const expressions + // used with const generics, e.g. `Foo<{N+1}>`, can work at all. + // + // Note that we do not supply the parent generics when using + // `min_const_generics`. + Some(parent_def_id.to_def_id()) + } else { + let parent_node = tcx.hir().get(tcx.hir().get_parent_node(hir_id)); + match parent_node { + // HACK(eddyb) this provides the correct generics for repeat + // expressions' count (i.e. `N` in `[x; N]`), and explicit + // `enum` discriminants (i.e. `D` in `enum Foo { Bar = D }`), + // as they shouldn't be able to cause query cycle errors. + Node::Expr(&Expr { kind: ExprKind::Repeat(_, ref constant), .. }) + if constant.hir_id() == hir_id => + { + Some(parent_def_id.to_def_id()) + } + Node::Variant(Variant { disr_expr: Some(ref constant), .. }) + if constant.hir_id == hir_id => + { + Some(parent_def_id.to_def_id()) + } + Node::Expr(&Expr { kind: ExprKind::ConstBlock(_), .. }) => { + Some(tcx.typeck_root_def_id(def_id)) + } + // Exclude `GlobalAsm` here which cannot have generics. + Node::Expr(&Expr { kind: ExprKind::InlineAsm(asm), .. }) + if asm.operands.iter().any(|(op, _op_sp)| match op { + hir::InlineAsmOperand::Const { anon_const } + | hir::InlineAsmOperand::SymFn { anon_const } => { + anon_const.hir_id == hir_id + } + _ => false, + }) => + { + Some(parent_def_id.to_def_id()) + } + _ => None, + } + } + } + Node::Expr(&hir::Expr { kind: hir::ExprKind::Closure { .. }, .. }) => { + Some(tcx.typeck_root_def_id(def_id)) + } + Node::Item(item) => match item.kind { + ItemKind::OpaqueTy(hir::OpaqueTy { + origin: + hir::OpaqueTyOrigin::FnReturn(fn_def_id) | hir::OpaqueTyOrigin::AsyncFn(fn_def_id), + in_trait, + .. + }) => { + if in_trait { + assert!(matches!(tcx.def_kind(fn_def_id), DefKind::AssocFn)) + } else { + assert!(matches!(tcx.def_kind(fn_def_id), DefKind::AssocFn | DefKind::Fn)) + } + Some(fn_def_id.to_def_id()) + } + ItemKind::OpaqueTy(hir::OpaqueTy { origin: hir::OpaqueTyOrigin::TyAlias, .. }) => { + let parent_id = tcx.hir().get_parent_item(hir_id); + assert_ne!(parent_id, hir::CRATE_OWNER_ID); + debug!("generics_of: parent of opaque ty {:?} is {:?}", def_id, parent_id); + // Opaque types are always nested within another item, and + // inherit the generics of the item. + Some(parent_id.to_def_id()) + } + _ => None, + }, + _ => None, + }; + + enum Defaults { + Allowed, + // See #36887 + FutureCompatDisallowed, + Deny, + } + + let no_generics = hir::Generics::empty(); + let ast_generics = node.generics().unwrap_or(&no_generics); + let (opt_self, allow_defaults) = match node { + Node::Item(item) => { + match item.kind { + ItemKind::Trait(..) | ItemKind::TraitAlias(..) => { + // Add in the self type parameter. + // + // Something of a hack: use the node id for the trait, also as + // the node id for the Self type parameter. + let opt_self = Some(ty::GenericParamDef { + index: 0, + name: kw::SelfUpper, + def_id, + pure_wrt_drop: false, + kind: ty::GenericParamDefKind::Type { + has_default: false, + synthetic: false, + }, + }); + + (opt_self, Defaults::Allowed) + } + ItemKind::TyAlias(..) + | ItemKind::Enum(..) + | ItemKind::Struct(..) + | ItemKind::OpaqueTy(..) + | ItemKind::Union(..) => (None, Defaults::Allowed), + _ => (None, Defaults::FutureCompatDisallowed), + } + } + + // GATs + Node::TraitItem(item) if matches!(item.kind, TraitItemKind::Type(..)) => { + (None, Defaults::Deny) + } + Node::ImplItem(item) if matches!(item.kind, ImplItemKind::TyAlias(..)) => { + (None, Defaults::Deny) + } + + _ => (None, Defaults::FutureCompatDisallowed), + }; + + let has_self = opt_self.is_some(); + let mut parent_has_self = false; + let mut own_start = has_self as u32; + let parent_count = parent_def_id.map_or(0, |def_id| { + let generics = tcx.generics_of(def_id); + assert!(!has_self); + parent_has_self = generics.has_self; + own_start = generics.count() as u32; + generics.parent_count + generics.params.len() + }); + + let mut params: Vec<_> = Vec::with_capacity(ast_generics.params.len() + has_self as usize); + + if let Some(opt_self) = opt_self { + params.push(opt_self); + } + + let early_lifetimes = early_bound_lifetimes_from_generics(tcx, ast_generics); + params.extend(early_lifetimes.enumerate().map(|(i, param)| ty::GenericParamDef { + name: param.name.ident().name, + index: own_start + i as u32, + def_id: tcx.hir().local_def_id(param.hir_id).to_def_id(), + pure_wrt_drop: param.pure_wrt_drop, + kind: ty::GenericParamDefKind::Lifetime, + })); + + // Now create the real type and const parameters. + let type_start = own_start - has_self as u32 + params.len() as u32; + let mut i = 0; + + const TYPE_DEFAULT_NOT_ALLOWED: &'static str = "defaults for type parameters are only allowed in \ + `struct`, `enum`, `type`, or `trait` definitions"; + + params.extend(ast_generics.params.iter().filter_map(|param| match param.kind { + GenericParamKind::Lifetime { .. } => None, + GenericParamKind::Type { ref default, synthetic, .. } => { + if default.is_some() { + match allow_defaults { + Defaults::Allowed => {} + Defaults::FutureCompatDisallowed + if tcx.features().default_type_parameter_fallback => {} + Defaults::FutureCompatDisallowed => { + tcx.struct_span_lint_hir( + lint::builtin::INVALID_TYPE_PARAM_DEFAULT, + param.hir_id, + param.span, + |lint| { + lint.build(TYPE_DEFAULT_NOT_ALLOWED).emit(); + }, + ); + } + Defaults::Deny => { + tcx.sess.span_err(param.span, TYPE_DEFAULT_NOT_ALLOWED); + } + } + } + + let kind = ty::GenericParamDefKind::Type { has_default: default.is_some(), synthetic }; + + let param_def = ty::GenericParamDef { + index: type_start + i as u32, + name: param.name.ident().name, + def_id: tcx.hir().local_def_id(param.hir_id).to_def_id(), + pure_wrt_drop: param.pure_wrt_drop, + kind, + }; + i += 1; + Some(param_def) + } + GenericParamKind::Const { default, .. } => { + if !matches!(allow_defaults, Defaults::Allowed) && default.is_some() { + tcx.sess.span_err( + param.span, + "defaults for const parameters are only allowed in \ + `struct`, `enum`, `type`, or `trait` definitions", + ); + } + + let param_def = ty::GenericParamDef { + index: type_start + i as u32, + name: param.name.ident().name, + def_id: tcx.hir().local_def_id(param.hir_id).to_def_id(), + pure_wrt_drop: param.pure_wrt_drop, + kind: ty::GenericParamDefKind::Const { has_default: default.is_some() }, + }; + i += 1; + Some(param_def) + } + })); + + // provide junk type parameter defs - the only place that + // cares about anything but the length is instantiation, + // and we don't do that for closures. + if let Node::Expr(&hir::Expr { + kind: hir::ExprKind::Closure(hir::Closure { movability: gen, .. }), + .. + }) = node + { + let dummy_args = if gen.is_some() { + &["<resume_ty>", "<yield_ty>", "<return_ty>", "<witness>", "<upvars>"][..] + } else { + &["<closure_kind>", "<closure_signature>", "<upvars>"][..] + }; + + params.extend(dummy_args.iter().enumerate().map(|(i, &arg)| ty::GenericParamDef { + index: type_start + i as u32, + name: Symbol::intern(arg), + def_id, + pure_wrt_drop: false, + kind: ty::GenericParamDefKind::Type { has_default: false, synthetic: false }, + })); + } + + // provide junk type parameter defs for const blocks. + if let Node::AnonConst(_) = node { + let parent_node = tcx.hir().get(tcx.hir().get_parent_node(hir_id)); + if let Node::Expr(&Expr { kind: ExprKind::ConstBlock(_), .. }) = parent_node { + params.push(ty::GenericParamDef { + index: type_start, + name: Symbol::intern("<const_ty>"), + def_id, + pure_wrt_drop: false, + kind: ty::GenericParamDefKind::Type { has_default: false, synthetic: false }, + }); + } + } + + let param_def_id_to_index = params.iter().map(|param| (param.def_id, param.index)).collect(); + + ty::Generics { + parent: parent_def_id, + parent_count, + params, + param_def_id_to_index, + has_self: has_self || parent_has_self, + has_late_bound_regions: has_late_bound_regions(tcx, node), + } +} + +fn are_suggestable_generic_args(generic_args: &[hir::GenericArg<'_>]) -> bool { + generic_args.iter().any(|arg| match arg { + hir::GenericArg::Type(ty) => is_suggestable_infer_ty(ty), + hir::GenericArg::Infer(_) => true, + _ => false, + }) +} + +/// Whether `ty` is a type with `_` placeholders that can be inferred. Used in diagnostics only to +/// use inference to provide suggestions for the appropriate type if possible. +fn is_suggestable_infer_ty(ty: &hir::Ty<'_>) -> bool { + debug!(?ty); + use hir::TyKind::*; + match &ty.kind { + Infer => true, + Slice(ty) => is_suggestable_infer_ty(ty), + Array(ty, length) => { + is_suggestable_infer_ty(ty) || matches!(length, hir::ArrayLen::Infer(_, _)) + } + Tup(tys) => tys.iter().any(is_suggestable_infer_ty), + Ptr(mut_ty) | Rptr(_, mut_ty) => is_suggestable_infer_ty(mut_ty.ty), + OpaqueDef(_, generic_args, _) => are_suggestable_generic_args(generic_args), + Path(hir::QPath::TypeRelative(ty, segment)) => { + is_suggestable_infer_ty(ty) || are_suggestable_generic_args(segment.args().args) + } + Path(hir::QPath::Resolved(ty_opt, hir::Path { segments, .. })) => { + ty_opt.map_or(false, is_suggestable_infer_ty) + || segments.iter().any(|segment| are_suggestable_generic_args(segment.args().args)) + } + _ => false, + } +} + +pub fn get_infer_ret_ty<'hir>(output: &'hir hir::FnRetTy<'hir>) -> Option<&'hir hir::Ty<'hir>> { + if let hir::FnRetTy::Return(ty) = output { + if is_suggestable_infer_ty(ty) { + return Some(&*ty); + } + } + None +} + +#[instrument(level = "debug", skip(tcx))] +fn fn_sig(tcx: TyCtxt<'_>, def_id: DefId) -> ty::PolyFnSig<'_> { + use rustc_hir::Node::*; + use rustc_hir::*; + + let def_id = def_id.expect_local(); + let hir_id = tcx.hir().local_def_id_to_hir_id(def_id); + + let icx = ItemCtxt::new(tcx, def_id.to_def_id()); + + match tcx.hir().get(hir_id) { + TraitItem(hir::TraitItem { + kind: TraitItemKind::Fn(sig, TraitFn::Provided(_)), + generics, + .. + }) + | Item(hir::Item { kind: ItemKind::Fn(sig, generics, _), .. }) => { + infer_return_ty_for_fn_sig(tcx, sig, generics, def_id, &icx) + } + + ImplItem(hir::ImplItem { kind: ImplItemKind::Fn(sig, _), generics, .. }) => { + // Do not try to inference the return type for a impl method coming from a trait + if let Item(hir::Item { kind: ItemKind::Impl(i), .. }) = + tcx.hir().get(tcx.hir().get_parent_node(hir_id)) + && i.of_trait.is_some() + { + <dyn AstConv<'_>>::ty_of_fn( + &icx, + hir_id, + sig.header.unsafety, + sig.header.abi, + sig.decl, + Some(generics), + None, + ) + } else { + infer_return_ty_for_fn_sig(tcx, sig, generics, def_id, &icx) + } + } + + TraitItem(hir::TraitItem { + kind: TraitItemKind::Fn(FnSig { header, decl, span: _ }, _), + generics, + .. + }) => <dyn AstConv<'_>>::ty_of_fn( + &icx, + hir_id, + header.unsafety, + header.abi, + decl, + Some(generics), + None, + ), + + ForeignItem(&hir::ForeignItem { kind: ForeignItemKind::Fn(fn_decl, _, _), .. }) => { + let abi = tcx.hir().get_foreign_abi(hir_id); + compute_sig_of_foreign_fn_decl(tcx, def_id.to_def_id(), fn_decl, abi) + } + + Ctor(data) | Variant(hir::Variant { data, .. }) if data.ctor_hir_id().is_some() => { + let ty = tcx.type_of(tcx.hir().get_parent_item(hir_id)); + let inputs = + data.fields().iter().map(|f| tcx.type_of(tcx.hir().local_def_id(f.hir_id))); + ty::Binder::dummy(tcx.mk_fn_sig( + inputs, + ty, + false, + hir::Unsafety::Normal, + abi::Abi::Rust, + )) + } + + Expr(&hir::Expr { kind: hir::ExprKind::Closure { .. }, .. }) => { + // Closure signatures are not like other function + // signatures and cannot be accessed through `fn_sig`. For + // example, a closure signature excludes the `self` + // argument. In any case they are embedded within the + // closure type as part of the `ClosureSubsts`. + // + // To get the signature of a closure, you should use the + // `sig` method on the `ClosureSubsts`: + // + // substs.as_closure().sig(def_id, tcx) + bug!( + "to get the signature of a closure, use `substs.as_closure().sig()` not `fn_sig()`", + ); + } + + x => { + bug!("unexpected sort of node in fn_sig(): {:?}", x); + } + } +} + +fn infer_return_ty_for_fn_sig<'tcx>( + tcx: TyCtxt<'tcx>, + sig: &hir::FnSig<'_>, + generics: &hir::Generics<'_>, + def_id: LocalDefId, + icx: &ItemCtxt<'tcx>, +) -> ty::PolyFnSig<'tcx> { + let hir_id = tcx.hir().local_def_id_to_hir_id(def_id); + + match get_infer_ret_ty(&sig.decl.output) { + Some(ty) => { + let fn_sig = tcx.typeck(def_id).liberated_fn_sigs()[hir_id]; + // Typeck doesn't expect erased regions to be returned from `type_of`. + let fn_sig = tcx.fold_regions(fn_sig, |r, _| match *r { + ty::ReErased => tcx.lifetimes.re_static, + _ => r, + }); + let fn_sig = ty::Binder::dummy(fn_sig); + + let mut visitor = HirPlaceholderCollector::default(); + visitor.visit_ty(ty); + let mut diag = bad_placeholder(tcx, visitor.0, "return type"); + let ret_ty = fn_sig.skip_binder().output(); + if ret_ty.is_suggestable(tcx, false) { + diag.span_suggestion( + ty.span, + "replace with the correct return type", + ret_ty, + Applicability::MachineApplicable, + ); + } else if matches!(ret_ty.kind(), ty::FnDef(..)) { + let fn_sig = ret_ty.fn_sig(tcx); + if fn_sig + .skip_binder() + .inputs_and_output + .iter() + .all(|t| t.is_suggestable(tcx, false)) + { + diag.span_suggestion( + ty.span, + "replace with the correct return type", + fn_sig, + Applicability::MachineApplicable, + ); + } + } else if ret_ty.is_closure() { + // We're dealing with a closure, so we should suggest using `impl Fn` or trait bounds + // to prevent the user from getting a papercut while trying to use the unique closure + // syntax (e.g. `[closure@src/lib.rs:2:5: 2:9]`). + diag.help("consider using an `Fn`, `FnMut`, or `FnOnce` trait bound"); + diag.note("for more information on `Fn` traits and closure types, see https://doc.rust-lang.org/book/ch13-01-closures.html"); + } + diag.emit(); + + fn_sig + } + None => <dyn AstConv<'_>>::ty_of_fn( + icx, + hir_id, + sig.header.unsafety, + sig.header.abi, + sig.decl, + Some(generics), + None, + ), + } +} + +fn impl_trait_ref(tcx: TyCtxt<'_>, def_id: DefId) -> Option<ty::TraitRef<'_>> { + let icx = ItemCtxt::new(tcx, def_id); + match tcx.hir().expect_item(def_id.expect_local()).kind { + hir::ItemKind::Impl(ref impl_) => impl_.of_trait.as_ref().map(|ast_trait_ref| { + let selfty = tcx.type_of(def_id); + <dyn AstConv<'_>>::instantiate_mono_trait_ref(&icx, ast_trait_ref, selfty) + }), + _ => bug!(), + } +} + +fn impl_polarity(tcx: TyCtxt<'_>, def_id: DefId) -> ty::ImplPolarity { + let is_rustc_reservation = tcx.has_attr(def_id, sym::rustc_reservation_impl); + let item = tcx.hir().expect_item(def_id.expect_local()); + match &item.kind { + hir::ItemKind::Impl(hir::Impl { + polarity: hir::ImplPolarity::Negative(span), + of_trait, + .. + }) => { + if is_rustc_reservation { + let span = span.to(of_trait.as_ref().map_or(*span, |t| t.path.span)); + tcx.sess.span_err(span, "reservation impls can't be negative"); + } + ty::ImplPolarity::Negative + } + hir::ItemKind::Impl(hir::Impl { + polarity: hir::ImplPolarity::Positive, + of_trait: None, + .. + }) => { + if is_rustc_reservation { + tcx.sess.span_err(item.span, "reservation impls can't be inherent"); + } + ty::ImplPolarity::Positive + } + hir::ItemKind::Impl(hir::Impl { + polarity: hir::ImplPolarity::Positive, + of_trait: Some(_), + .. + }) => { + if is_rustc_reservation { + ty::ImplPolarity::Reservation + } else { + ty::ImplPolarity::Positive + } + } + item => bug!("impl_polarity: {:?} not an impl", item), + } +} + +/// Returns the early-bound lifetimes declared in this generics +/// listing. For anything other than fns/methods, this is just all +/// the lifetimes that are declared. For fns or methods, we have to +/// screen out those that do not appear in any where-clauses etc using +/// `resolve_lifetime::early_bound_lifetimes`. +fn early_bound_lifetimes_from_generics<'a, 'tcx: 'a>( + tcx: TyCtxt<'tcx>, + generics: &'a hir::Generics<'a>, +) -> impl Iterator<Item = &'a hir::GenericParam<'a>> + Captures<'tcx> { + generics.params.iter().filter(move |param| match param.kind { + GenericParamKind::Lifetime { .. } => !tcx.is_late_bound(param.hir_id), + _ => false, + }) +} + +/// Returns a list of type predicates for the definition with ID `def_id`, including inferred +/// lifetime constraints. This includes all predicates returned by `explicit_predicates_of`, plus +/// inferred constraints concerning which regions outlive other regions. +#[instrument(level = "debug", skip(tcx))] +fn predicates_defined_on(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericPredicates<'_> { + let mut result = tcx.explicit_predicates_of(def_id); + debug!("predicates_defined_on: explicit_predicates_of({:?}) = {:?}", def_id, result,); + let inferred_outlives = tcx.inferred_outlives_of(def_id); + if !inferred_outlives.is_empty() { + debug!( + "predicates_defined_on: inferred_outlives_of({:?}) = {:?}", + def_id, inferred_outlives, + ); + if result.predicates.is_empty() { + result.predicates = inferred_outlives; + } else { + result.predicates = tcx + .arena + .alloc_from_iter(result.predicates.iter().chain(inferred_outlives).copied()); + } + } + + debug!("predicates_defined_on({:?}) = {:?}", def_id, result); + result +} + +/// Returns a list of all type predicates (explicit and implicit) for the definition with +/// ID `def_id`. This includes all predicates returned by `predicates_defined_on`, plus +/// `Self: Trait` predicates for traits. +fn predicates_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericPredicates<'_> { + let mut result = tcx.predicates_defined_on(def_id); + + if tcx.is_trait(def_id) { + // For traits, add `Self: Trait` predicate. This is + // not part of the predicates that a user writes, but it + // is something that one must prove in order to invoke a + // method or project an associated type. + // + // In the chalk setup, this predicate is not part of the + // "predicates" for a trait item. But it is useful in + // rustc because if you directly (e.g.) invoke a trait + // method like `Trait::method(...)`, you must naturally + // prove that the trait applies to the types that were + // used, and adding the predicate into this list ensures + // that this is done. + // + // We use a DUMMY_SP here as a way to signal trait bounds that come + // from the trait itself that *shouldn't* be shown as the source of + // an obligation and instead be skipped. Otherwise we'd use + // `tcx.def_span(def_id);` + + let constness = if tcx.has_attr(def_id, sym::const_trait) { + ty::BoundConstness::ConstIfConst + } else { + ty::BoundConstness::NotConst + }; + + let span = rustc_span::DUMMY_SP; + result.predicates = + tcx.arena.alloc_from_iter(result.predicates.iter().copied().chain(std::iter::once(( + ty::TraitRef::identity(tcx, def_id).with_constness(constness).to_predicate(tcx), + span, + )))); + } + debug!("predicates_of(def_id={:?}) = {:?}", def_id, result); + result +} + +/// Returns a list of user-specified type predicates for the definition with ID `def_id`. +/// N.B., this does not include any implied/inferred constraints. +#[instrument(level = "trace", skip(tcx), ret)] +fn gather_explicit_predicates_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericPredicates<'_> { + use rustc_hir::*; + + let hir_id = tcx.hir().local_def_id_to_hir_id(def_id.expect_local()); + let node = tcx.hir().get(hir_id); + + let mut is_trait = None; + let mut is_default_impl_trait = None; + + let icx = ItemCtxt::new(tcx, def_id); + + const NO_GENERICS: &hir::Generics<'_> = hir::Generics::empty(); + + // We use an `IndexSet` to preserves order of insertion. + // Preserving the order of insertion is important here so as not to break UI tests. + let mut predicates: FxIndexSet<(ty::Predicate<'_>, Span)> = FxIndexSet::default(); + + let ast_generics = match node { + Node::TraitItem(item) => item.generics, + + Node::ImplItem(item) => item.generics, + + Node::Item(item) => { + match item.kind { + ItemKind::Impl(ref impl_) => { + if impl_.defaultness.is_default() { + is_default_impl_trait = tcx.impl_trait_ref(def_id).map(ty::Binder::dummy); + } + &impl_.generics + } + ItemKind::Fn(.., ref generics, _) + | ItemKind::TyAlias(_, ref generics) + | ItemKind::Enum(_, ref generics) + | ItemKind::Struct(_, ref generics) + | ItemKind::Union(_, ref generics) => *generics, + + ItemKind::Trait(_, _, ref generics, ..) => { + is_trait = Some(ty::TraitRef::identity(tcx, def_id)); + *generics + } + ItemKind::TraitAlias(ref generics, _) => { + is_trait = Some(ty::TraitRef::identity(tcx, def_id)); + *generics + } + ItemKind::OpaqueTy(OpaqueTy { + origin: hir::OpaqueTyOrigin::AsyncFn(..) | hir::OpaqueTyOrigin::FnReturn(..), + .. + }) => { + // return-position impl trait + // + // We don't inherit predicates from the parent here: + // If we have, say `fn f<'a, T: 'a>() -> impl Sized {}` + // then the return type is `f::<'static, T>::{{opaque}}`. + // + // If we inherited the predicates of `f` then we would + // require that `T: 'static` to show that the return + // type is well-formed. + // + // The only way to have something with this opaque type + // is from the return type of the containing function, + // which will ensure that the function's predicates + // hold. + return ty::GenericPredicates { parent: None, predicates: &[] }; + } + ItemKind::OpaqueTy(OpaqueTy { + ref generics, + origin: hir::OpaqueTyOrigin::TyAlias, + .. + }) => { + // type-alias impl trait + generics + } + + _ => NO_GENERICS, + } + } + + Node::ForeignItem(item) => match item.kind { + ForeignItemKind::Static(..) => NO_GENERICS, + ForeignItemKind::Fn(_, _, ref generics) => *generics, + ForeignItemKind::Type => NO_GENERICS, + }, + + _ => NO_GENERICS, + }; + + let generics = tcx.generics_of(def_id); + let parent_count = generics.parent_count as u32; + let has_own_self = generics.has_self && parent_count == 0; + + // Below we'll consider the bounds on the type parameters (including `Self`) + // and the explicit where-clauses, but to get the full set of predicates + // on a trait we need to add in the supertrait bounds and bounds found on + // associated types. + if let Some(_trait_ref) = is_trait { + predicates.extend(tcx.super_predicates_of(def_id).predicates.iter().cloned()); + } + + // In default impls, we can assume that the self type implements + // the trait. So in: + // + // default impl Foo for Bar { .. } + // + // we add a default where clause `Foo: Bar`. We do a similar thing for traits + // (see below). Recall that a default impl is not itself an impl, but rather a + // set of defaults that can be incorporated into another impl. + if let Some(trait_ref) = is_default_impl_trait { + predicates.insert((trait_ref.without_const().to_predicate(tcx), tcx.def_span(def_id))); + } + + // Collect the region predicates that were declared inline as + // well. In the case of parameters declared on a fn or method, we + // have to be careful to only iterate over early-bound regions. + let mut index = parent_count + + has_own_self as u32 + + early_bound_lifetimes_from_generics(tcx, ast_generics).count() as u32; + + trace!(?predicates); + trace!(?ast_generics); + + // Collect the predicates that were written inline by the user on each + // type parameter (e.g., `<T: Foo>`). + for param in ast_generics.params { + match param.kind { + // We already dealt with early bound lifetimes above. + GenericParamKind::Lifetime { .. } => (), + GenericParamKind::Type { .. } => { + let name = param.name.ident().name; + let param_ty = ty::ParamTy::new(index, name).to_ty(tcx); + index += 1; + + let mut bounds = Bounds::default(); + // Params are implicitly sized unless a `?Sized` bound is found + <dyn AstConv<'_>>::add_implicitly_sized( + &icx, + &mut bounds, + &[], + Some((param.hir_id, ast_generics.predicates)), + param.span, + ); + trace!(?bounds); + predicates.extend(bounds.predicates(tcx, param_ty)); + trace!(?predicates); + } + GenericParamKind::Const { .. } => { + // Bounds on const parameters are currently not possible. + index += 1; + } + } + } + + trace!(?predicates); + // Add in the bounds that appear in the where-clause. + for predicate in ast_generics.predicates { + match predicate { + hir::WherePredicate::BoundPredicate(bound_pred) => { + let ty = icx.to_ty(bound_pred.bounded_ty); + let bound_vars = icx.tcx.late_bound_vars(bound_pred.bounded_ty.hir_id); + + // Keep the type around in a dummy predicate, in case of no bounds. + // That way, `where Ty:` is not a complete noop (see #53696) and `Ty` + // is still checked for WF. + if bound_pred.bounds.is_empty() { + if let ty::Param(_) = ty.kind() { + // This is a `where T:`, which can be in the HIR from the + // transformation that moves `?Sized` to `T`'s declaration. + // We can skip the predicate because type parameters are + // trivially WF, but also we *should*, to avoid exposing + // users who never wrote `where Type:,` themselves, to + // compiler/tooling bugs from not handling WF predicates. + } else { + let span = bound_pred.bounded_ty.span; + let predicate = ty::Binder::bind_with_vars( + ty::PredicateKind::WellFormed(ty.into()), + bound_vars, + ); + predicates.insert((predicate.to_predicate(tcx), span)); + } + } + + let mut bounds = Bounds::default(); + <dyn AstConv<'_>>::add_bounds( + &icx, + ty, + bound_pred.bounds.iter(), + &mut bounds, + bound_vars, + ); + predicates.extend(bounds.predicates(tcx, ty)); + } + + hir::WherePredicate::RegionPredicate(region_pred) => { + let r1 = <dyn AstConv<'_>>::ast_region_to_region(&icx, ®ion_pred.lifetime, None); + predicates.extend(region_pred.bounds.iter().map(|bound| { + let (r2, span) = match bound { + hir::GenericBound::Outlives(lt) => { + (<dyn AstConv<'_>>::ast_region_to_region(&icx, lt, None), lt.span) + } + _ => bug!(), + }; + let pred = ty::Binder::dummy(ty::PredicateKind::RegionOutlives( + ty::OutlivesPredicate(r1, r2), + )) + .to_predicate(icx.tcx); + + (pred, span) + })) + } + + hir::WherePredicate::EqPredicate(..) => { + // FIXME(#20041) + } + } + } + + if tcx.features().generic_const_exprs { + predicates.extend(const_evaluatable_predicates_of(tcx, def_id.expect_local())); + } + + let mut predicates: Vec<_> = predicates.into_iter().collect(); + + // Subtle: before we store the predicates into the tcx, we + // sort them so that predicates like `T: Foo<Item=U>` come + // before uses of `U`. This avoids false ambiguity errors + // in trait checking. See `setup_constraining_predicates` + // for details. + if let Node::Item(&Item { kind: ItemKind::Impl { .. }, .. }) = node { + let self_ty = tcx.type_of(def_id); + let trait_ref = tcx.impl_trait_ref(def_id); + cgp::setup_constraining_predicates( + tcx, + &mut predicates, + trait_ref, + &mut cgp::parameters_for_impl(self_ty, trait_ref), + ); + } + + ty::GenericPredicates { + parent: generics.parent, + predicates: tcx.arena.alloc_from_iter(predicates), + } +} + +fn const_evaluatable_predicates_of<'tcx>( + tcx: TyCtxt<'tcx>, + def_id: LocalDefId, +) -> FxIndexSet<(ty::Predicate<'tcx>, Span)> { + struct ConstCollector<'tcx> { + tcx: TyCtxt<'tcx>, + preds: FxIndexSet<(ty::Predicate<'tcx>, Span)>, + } + + impl<'tcx> intravisit::Visitor<'tcx> for ConstCollector<'tcx> { + fn visit_anon_const(&mut self, c: &'tcx hir::AnonConst) { + let def_id = self.tcx.hir().local_def_id(c.hir_id); + let ct = ty::Const::from_anon_const(self.tcx, def_id); + if let ty::ConstKind::Unevaluated(uv) = ct.kind() { + let span = self.tcx.hir().span(c.hir_id); + self.preds.insert(( + ty::Binder::dummy(ty::PredicateKind::ConstEvaluatable(uv)) + .to_predicate(self.tcx), + span, + )); + } + } + + fn visit_const_param_default(&mut self, _param: HirId, _ct: &'tcx hir::AnonConst) { + // Do not look into const param defaults, + // these get checked when they are actually instantiated. + // + // We do not want the following to error: + // + // struct Foo<const N: usize, const M: usize = { N + 1 }>; + // struct Bar<const N: usize>(Foo<N, 3>); + } + } + + let hir_id = tcx.hir().local_def_id_to_hir_id(def_id); + let node = tcx.hir().get(hir_id); + + let mut collector = ConstCollector { tcx, preds: FxIndexSet::default() }; + if let hir::Node::Item(item) = node && let hir::ItemKind::Impl(ref impl_) = item.kind { + if let Some(of_trait) = &impl_.of_trait { + debug!("const_evaluatable_predicates_of({:?}): visit impl trait_ref", def_id); + collector.visit_trait_ref(of_trait); + } + + debug!("const_evaluatable_predicates_of({:?}): visit_self_ty", def_id); + collector.visit_ty(impl_.self_ty); + } + + if let Some(generics) = node.generics() { + debug!("const_evaluatable_predicates_of({:?}): visit_generics", def_id); + collector.visit_generics(generics); + } + + if let Some(fn_sig) = tcx.hir().fn_sig_by_hir_id(hir_id) { + debug!("const_evaluatable_predicates_of({:?}): visit_fn_decl", def_id); + collector.visit_fn_decl(fn_sig.decl); + } + debug!("const_evaluatable_predicates_of({:?}) = {:?}", def_id, collector.preds); + + collector.preds +} + +fn trait_explicit_predicates_and_bounds( + tcx: TyCtxt<'_>, + def_id: LocalDefId, +) -> ty::GenericPredicates<'_> { + assert_eq!(tcx.def_kind(def_id), DefKind::Trait); + gather_explicit_predicates_of(tcx, def_id.to_def_id()) +} + +fn explicit_predicates_of<'tcx>(tcx: TyCtxt<'tcx>, def_id: DefId) -> ty::GenericPredicates<'tcx> { + let def_kind = tcx.def_kind(def_id); + if let DefKind::Trait = def_kind { + // Remove bounds on associated types from the predicates, they will be + // returned by `explicit_item_bounds`. + let predicates_and_bounds = tcx.trait_explicit_predicates_and_bounds(def_id.expect_local()); + let trait_identity_substs = InternalSubsts::identity_for_item(tcx, def_id); + + let is_assoc_item_ty = |ty: Ty<'tcx>| { + // For a predicate from a where clause to become a bound on an + // associated type: + // * It must use the identity substs of the item. + // * Since any generic parameters on the item are not in scope, + // this means that the item is not a GAT, and its identity + // substs are the same as the trait's. + // * It must be an associated type for this trait (*not* a + // supertrait). + if let ty::Projection(projection) = ty.kind() { + projection.substs == trait_identity_substs + && tcx.associated_item(projection.item_def_id).container_id(tcx) == def_id + } else { + false + } + }; + + let predicates: Vec<_> = predicates_and_bounds + .predicates + .iter() + .copied() + .filter(|(pred, _)| match pred.kind().skip_binder() { + ty::PredicateKind::Trait(tr) => !is_assoc_item_ty(tr.self_ty()), + ty::PredicateKind::Projection(proj) => { + !is_assoc_item_ty(proj.projection_ty.self_ty()) + } + ty::PredicateKind::TypeOutlives(outlives) => !is_assoc_item_ty(outlives.0), + _ => true, + }) + .collect(); + if predicates.len() == predicates_and_bounds.predicates.len() { + predicates_and_bounds + } else { + ty::GenericPredicates { + parent: predicates_and_bounds.parent, + predicates: tcx.arena.alloc_slice(&predicates), + } + } + } else { + if matches!(def_kind, DefKind::AnonConst) && tcx.lazy_normalization() { + let hir_id = tcx.hir().local_def_id_to_hir_id(def_id.expect_local()); + if tcx.hir().opt_const_param_default_param_hir_id(hir_id).is_some() { + // In `generics_of` we set the generics' parent to be our parent's parent which means that + // we lose out on the predicates of our actual parent if we dont return those predicates here. + // (See comment in `generics_of` for more information on why the parent shenanigans is necessary) + // + // struct Foo<T, const N: usize = { <T as Trait>::ASSOC }>(T) where T: Trait; + // ^^^ ^^^^^^^^^^^^^^^^^^^^^^^ the def id we are calling + // ^^^ explicit_predicates_of on + // parent item we dont have set as the + // parent of generics returned by `generics_of` + // + // In the above code we want the anon const to have predicates in its param env for `T: Trait` + let item_def_id = tcx.hir().get_parent_item(hir_id); + // In the above code example we would be calling `explicit_predicates_of(Foo)` here + return tcx.explicit_predicates_of(item_def_id); + } + } + gather_explicit_predicates_of(tcx, def_id) + } +} + +/// Converts a specific `GenericBound` from the AST into a set of +/// predicates that apply to the self type. A vector is returned +/// because this can be anywhere from zero predicates (`T: ?Sized` adds no +/// predicates) to one (`T: Foo`) to many (`T: Bar<X = i32>` adds `T: Bar` +/// and `<T as Bar>::X == i32`). +fn predicates_from_bound<'tcx>( + astconv: &dyn AstConv<'tcx>, + param_ty: Ty<'tcx>, + bound: &'tcx hir::GenericBound<'tcx>, + bound_vars: &'tcx ty::List<ty::BoundVariableKind>, +) -> Vec<(ty::Predicate<'tcx>, Span)> { + let mut bounds = Bounds::default(); + astconv.add_bounds(param_ty, [bound].into_iter(), &mut bounds, bound_vars); + bounds.predicates(astconv.tcx(), param_ty).collect() +} + +fn compute_sig_of_foreign_fn_decl<'tcx>( + tcx: TyCtxt<'tcx>, + def_id: DefId, + decl: &'tcx hir::FnDecl<'tcx>, + abi: abi::Abi, +) -> ty::PolyFnSig<'tcx> { + let unsafety = if abi == abi::Abi::RustIntrinsic { + intrinsic_operation_unsafety(tcx.item_name(def_id)) + } else { + hir::Unsafety::Unsafe + }; + let hir_id = tcx.hir().local_def_id_to_hir_id(def_id.expect_local()); + let fty = <dyn AstConv<'_>>::ty_of_fn( + &ItemCtxt::new(tcx, def_id), + hir_id, + unsafety, + abi, + decl, + None, + None, + ); + + // Feature gate SIMD types in FFI, since I am not sure that the + // ABIs are handled at all correctly. -huonw + if abi != abi::Abi::RustIntrinsic + && abi != abi::Abi::PlatformIntrinsic + && !tcx.features().simd_ffi + { + let check = |ast_ty: &hir::Ty<'_>, ty: Ty<'_>| { + if ty.is_simd() { + let snip = tcx + .sess + .source_map() + .span_to_snippet(ast_ty.span) + .map_or_else(|_| String::new(), |s| format!(" `{}`", s)); + tcx.sess + .struct_span_err( + ast_ty.span, + &format!( + "use of SIMD type{} in FFI is highly experimental and \ + may result in invalid code", + snip + ), + ) + .help("add `#![feature(simd_ffi)]` to the crate attributes to enable") + .emit(); + } + }; + for (input, ty) in iter::zip(decl.inputs, fty.inputs().skip_binder()) { + check(input, *ty) + } + if let hir::FnRetTy::Return(ref ty) = decl.output { + check(ty, fty.output().skip_binder()) + } + } + + fty +} + +fn is_foreign_item(tcx: TyCtxt<'_>, def_id: DefId) -> bool { + match tcx.hir().get_if_local(def_id) { + Some(Node::ForeignItem(..)) => true, + Some(_) => false, + _ => bug!("is_foreign_item applied to non-local def-id {:?}", def_id), + } +} + +fn generator_kind(tcx: TyCtxt<'_>, def_id: DefId) -> Option<hir::GeneratorKind> { + match tcx.hir().get_if_local(def_id) { + Some(Node::Expr(&rustc_hir::Expr { + kind: rustc_hir::ExprKind::Closure(&rustc_hir::Closure { body, .. }), + .. + })) => tcx.hir().body(body).generator_kind(), + Some(_) => None, + _ => bug!("generator_kind applied to non-local def-id {:?}", def_id), + } +} + +fn from_target_feature( + tcx: TyCtxt<'_>, + attr: &ast::Attribute, + supported_target_features: &FxHashMap<String, Option<Symbol>>, + target_features: &mut Vec<Symbol>, +) { + let Some(list) = attr.meta_item_list() else { return }; + let bad_item = |span| { + let msg = "malformed `target_feature` attribute input"; + let code = "enable = \"..\""; + tcx.sess + .struct_span_err(span, msg) + .span_suggestion(span, "must be of the form", code, Applicability::HasPlaceholders) + .emit(); + }; + let rust_features = tcx.features(); + for item in list { + // Only `enable = ...` is accepted in the meta-item list. + if !item.has_name(sym::enable) { + bad_item(item.span()); + continue; + } + + // Must be of the form `enable = "..."` (a string). + let Some(value) = item.value_str() else { + bad_item(item.span()); + continue; + }; + + // We allow comma separation to enable multiple features. + target_features.extend(value.as_str().split(',').filter_map(|feature| { + let Some(feature_gate) = supported_target_features.get(feature) else { + let msg = + format!("the feature named `{}` is not valid for this target", feature); + let mut err = tcx.sess.struct_span_err(item.span(), &msg); + err.span_label( + item.span(), + format!("`{}` is not valid for this target", feature), + ); + if let Some(stripped) = feature.strip_prefix('+') { + let valid = supported_target_features.contains_key(stripped); + if valid { + err.help("consider removing the leading `+` in the feature name"); + } + } + err.emit(); + return None; + }; + + // Only allow features whose feature gates have been enabled. + let allowed = match feature_gate.as_ref().copied() { + Some(sym::arm_target_feature) => rust_features.arm_target_feature, + Some(sym::hexagon_target_feature) => rust_features.hexagon_target_feature, + Some(sym::powerpc_target_feature) => rust_features.powerpc_target_feature, + Some(sym::mips_target_feature) => rust_features.mips_target_feature, + Some(sym::riscv_target_feature) => rust_features.riscv_target_feature, + Some(sym::avx512_target_feature) => rust_features.avx512_target_feature, + Some(sym::sse4a_target_feature) => rust_features.sse4a_target_feature, + Some(sym::tbm_target_feature) => rust_features.tbm_target_feature, + Some(sym::wasm_target_feature) => rust_features.wasm_target_feature, + Some(sym::cmpxchg16b_target_feature) => rust_features.cmpxchg16b_target_feature, + Some(sym::movbe_target_feature) => rust_features.movbe_target_feature, + Some(sym::rtm_target_feature) => rust_features.rtm_target_feature, + Some(sym::f16c_target_feature) => rust_features.f16c_target_feature, + Some(sym::ermsb_target_feature) => rust_features.ermsb_target_feature, + Some(sym::bpf_target_feature) => rust_features.bpf_target_feature, + Some(sym::aarch64_ver_target_feature) => rust_features.aarch64_ver_target_feature, + Some(name) => bug!("unknown target feature gate {}", name), + None => true, + }; + if !allowed { + feature_err( + &tcx.sess.parse_sess, + feature_gate.unwrap(), + item.span(), + &format!("the target feature `{}` is currently unstable", feature), + ) + .emit(); + } + Some(Symbol::intern(feature)) + })); + } +} + +fn linkage_by_name(tcx: TyCtxt<'_>, def_id: LocalDefId, name: &str) -> Linkage { + use rustc_middle::mir::mono::Linkage::*; + + // Use the names from src/llvm/docs/LangRef.rst here. Most types are only + // applicable to variable declarations and may not really make sense for + // Rust code in the first place but allow them anyway and trust that the + // user knows what they're doing. Who knows, unanticipated use cases may pop + // up in the future. + // + // ghost, dllimport, dllexport and linkonce_odr_autohide are not supported + // and don't have to be, LLVM treats them as no-ops. + match name { + "appending" => Appending, + "available_externally" => AvailableExternally, + "common" => Common, + "extern_weak" => ExternalWeak, + "external" => External, + "internal" => Internal, + "linkonce" => LinkOnceAny, + "linkonce_odr" => LinkOnceODR, + "private" => Private, + "weak" => WeakAny, + "weak_odr" => WeakODR, + _ => tcx.sess.span_fatal(tcx.def_span(def_id), "invalid linkage specified"), + } +} + +fn codegen_fn_attrs(tcx: TyCtxt<'_>, did: DefId) -> CodegenFnAttrs { + if cfg!(debug_assertions) { + let def_kind = tcx.def_kind(did); + assert!( + def_kind.has_codegen_attrs(), + "unexpected `def_kind` in `codegen_fn_attrs`: {def_kind:?}", + ); + } + + let did = did.expect_local(); + let attrs = tcx.hir().attrs(tcx.hir().local_def_id_to_hir_id(did)); + let mut codegen_fn_attrs = CodegenFnAttrs::new(); + if tcx.should_inherit_track_caller(did) { + codegen_fn_attrs.flags |= CodegenFnAttrFlags::TRACK_CALLER; + } + + // The panic_no_unwind function called by TerminatorKind::Abort will never + // unwind. If the panic handler that it invokes unwind then it will simply + // call the panic handler again. + if Some(did.to_def_id()) == tcx.lang_items().panic_no_unwind() { + codegen_fn_attrs.flags |= CodegenFnAttrFlags::NEVER_UNWIND; + } + + let supported_target_features = tcx.supported_target_features(LOCAL_CRATE); + + let mut inline_span = None; + let mut link_ordinal_span = None; + let mut no_sanitize_span = None; + for attr in attrs.iter() { + if attr.has_name(sym::cold) { + codegen_fn_attrs.flags |= CodegenFnAttrFlags::COLD; + } else if attr.has_name(sym::rustc_allocator) { + codegen_fn_attrs.flags |= CodegenFnAttrFlags::ALLOCATOR; + } else if attr.has_name(sym::ffi_returns_twice) { + if tcx.is_foreign_item(did) { + codegen_fn_attrs.flags |= CodegenFnAttrFlags::FFI_RETURNS_TWICE; + } else { + // `#[ffi_returns_twice]` is only allowed `extern fn`s. + struct_span_err!( + tcx.sess, + attr.span, + E0724, + "`#[ffi_returns_twice]` may only be used on foreign functions" + ) + .emit(); + } + } else if attr.has_name(sym::ffi_pure) { + if tcx.is_foreign_item(did) { + if attrs.iter().any(|a| a.has_name(sym::ffi_const)) { + // `#[ffi_const]` functions cannot be `#[ffi_pure]` + struct_span_err!( + tcx.sess, + attr.span, + E0757, + "`#[ffi_const]` function cannot be `#[ffi_pure]`" + ) + .emit(); + } else { + codegen_fn_attrs.flags |= CodegenFnAttrFlags::FFI_PURE; + } + } else { + // `#[ffi_pure]` is only allowed on foreign functions + struct_span_err!( + tcx.sess, + attr.span, + E0755, + "`#[ffi_pure]` may only be used on foreign functions" + ) + .emit(); + } + } else if attr.has_name(sym::ffi_const) { + if tcx.is_foreign_item(did) { + codegen_fn_attrs.flags |= CodegenFnAttrFlags::FFI_CONST; + } else { + // `#[ffi_const]` is only allowed on foreign functions + struct_span_err!( + tcx.sess, + attr.span, + E0756, + "`#[ffi_const]` may only be used on foreign functions" + ) + .emit(); + } + } else if attr.has_name(sym::rustc_allocator_nounwind) { + codegen_fn_attrs.flags |= CodegenFnAttrFlags::NEVER_UNWIND; + } else if attr.has_name(sym::rustc_reallocator) { + codegen_fn_attrs.flags |= CodegenFnAttrFlags::REALLOCATOR; + } else if attr.has_name(sym::rustc_deallocator) { + codegen_fn_attrs.flags |= CodegenFnAttrFlags::DEALLOCATOR; + } else if attr.has_name(sym::rustc_allocator_zeroed) { + codegen_fn_attrs.flags |= CodegenFnAttrFlags::ALLOCATOR_ZEROED; + } else if attr.has_name(sym::naked) { + codegen_fn_attrs.flags |= CodegenFnAttrFlags::NAKED; + } else if attr.has_name(sym::no_mangle) { + codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_MANGLE; + } else if attr.has_name(sym::no_coverage) { + codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_COVERAGE; + } else if attr.has_name(sym::rustc_std_internal_symbol) { + codegen_fn_attrs.flags |= CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL; + } else if attr.has_name(sym::used) { + let inner = attr.meta_item_list(); + match inner.as_deref() { + Some([item]) if item.has_name(sym::linker) => { + if !tcx.features().used_with_arg { + feature_err( + &tcx.sess.parse_sess, + sym::used_with_arg, + attr.span, + "`#[used(linker)]` is currently unstable", + ) + .emit(); + } + codegen_fn_attrs.flags |= CodegenFnAttrFlags::USED_LINKER; + } + Some([item]) if item.has_name(sym::compiler) => { + if !tcx.features().used_with_arg { + feature_err( + &tcx.sess.parse_sess, + sym::used_with_arg, + attr.span, + "`#[used(compiler)]` is currently unstable", + ) + .emit(); + } + codegen_fn_attrs.flags |= CodegenFnAttrFlags::USED; + } + Some(_) => { + tcx.sess.emit_err(errors::ExpectedUsedSymbol { span: attr.span }); + } + None => { + // Unfortunately, unconditionally using `llvm.used` causes + // issues in handling `.init_array` with the gold linker, + // but using `llvm.compiler.used` caused a nontrival amount + // of unintentional ecosystem breakage -- particularly on + // Mach-O targets. + // + // As a result, we emit `llvm.compiler.used` only on ELF + // targets. This is somewhat ad-hoc, but actually follows + // our pre-LLVM 13 behavior (prior to the ecosystem + // breakage), and seems to match `clang`'s behavior as well + // (both before and after LLVM 13), possibly because they + // have similar compatibility concerns to us. See + // https://github.com/rust-lang/rust/issues/47384#issuecomment-1019080146 + // and following comments for some discussion of this, as + // well as the comments in `rustc_codegen_llvm` where these + // flags are handled. + // + // Anyway, to be clear: this is still up in the air + // somewhat, and is subject to change in the future (which + // is a good thing, because this would ideally be a bit + // more firmed up). + let is_like_elf = !(tcx.sess.target.is_like_osx + || tcx.sess.target.is_like_windows + || tcx.sess.target.is_like_wasm); + codegen_fn_attrs.flags |= if is_like_elf { + CodegenFnAttrFlags::USED + } else { + CodegenFnAttrFlags::USED_LINKER + }; + } + } + } else if attr.has_name(sym::cmse_nonsecure_entry) { + if !matches!(tcx.fn_sig(did).abi(), abi::Abi::C { .. }) { + struct_span_err!( + tcx.sess, + attr.span, + E0776, + "`#[cmse_nonsecure_entry]` requires C ABI" + ) + .emit(); + } + if !tcx.sess.target.llvm_target.contains("thumbv8m") { + struct_span_err!(tcx.sess, attr.span, E0775, "`#[cmse_nonsecure_entry]` is only valid for targets with the TrustZone-M extension") + .emit(); + } + codegen_fn_attrs.flags |= CodegenFnAttrFlags::CMSE_NONSECURE_ENTRY; + } else if attr.has_name(sym::thread_local) { + codegen_fn_attrs.flags |= CodegenFnAttrFlags::THREAD_LOCAL; + } else if attr.has_name(sym::track_caller) { + if !tcx.is_closure(did.to_def_id()) && tcx.fn_sig(did).abi() != abi::Abi::Rust { + struct_span_err!(tcx.sess, attr.span, E0737, "`#[track_caller]` requires Rust ABI") + .emit(); + } + if tcx.is_closure(did.to_def_id()) && !tcx.features().closure_track_caller { + feature_err( + &tcx.sess.parse_sess, + sym::closure_track_caller, + attr.span, + "`#[track_caller]` on closures is currently unstable", + ) + .emit(); + } + codegen_fn_attrs.flags |= CodegenFnAttrFlags::TRACK_CALLER; + } else if attr.has_name(sym::export_name) { + if let Some(s) = attr.value_str() { + if s.as_str().contains('\0') { + // `#[export_name = ...]` will be converted to a null-terminated string, + // so it may not contain any null characters. + struct_span_err!( + tcx.sess, + attr.span, + E0648, + "`export_name` may not contain null characters" + ) + .emit(); + } + codegen_fn_attrs.export_name = Some(s); + } + } else if attr.has_name(sym::target_feature) { + if !tcx.is_closure(did.to_def_id()) + && tcx.fn_sig(did).unsafety() == hir::Unsafety::Normal + { + if tcx.sess.target.is_like_wasm || tcx.sess.opts.actually_rustdoc { + // The `#[target_feature]` attribute is allowed on + // WebAssembly targets on all functions, including safe + // ones. Other targets require that `#[target_feature]` is + // only applied to unsafe functions (pending the + // `target_feature_11` feature) because on most targets + // execution of instructions that are not supported is + // considered undefined behavior. For WebAssembly which is a + // 100% safe target at execution time it's not possible to + // execute undefined instructions, and even if a future + // feature was added in some form for this it would be a + // deterministic trap. There is no undefined behavior when + // executing WebAssembly so `#[target_feature]` is allowed + // on safe functions (but again, only for WebAssembly) + // + // Note that this is also allowed if `actually_rustdoc` so + // if a target is documenting some wasm-specific code then + // it's not spuriously denied. + } else if !tcx.features().target_feature_11 { + let mut err = feature_err( + &tcx.sess.parse_sess, + sym::target_feature_11, + attr.span, + "`#[target_feature(..)]` can only be applied to `unsafe` functions", + ); + err.span_label(tcx.def_span(did), "not an `unsafe` function"); + err.emit(); + } else { + check_target_feature_trait_unsafe(tcx, did, attr.span); + } + } + from_target_feature( + tcx, + attr, + supported_target_features, + &mut codegen_fn_attrs.target_features, + ); + } else if attr.has_name(sym::linkage) { + if let Some(val) = attr.value_str() { + codegen_fn_attrs.linkage = Some(linkage_by_name(tcx, did, val.as_str())); + } + } else if attr.has_name(sym::link_section) { + if let Some(val) = attr.value_str() { + if val.as_str().bytes().any(|b| b == 0) { + let msg = format!( + "illegal null byte in link_section \ + value: `{}`", + &val + ); + tcx.sess.span_err(attr.span, &msg); + } else { + codegen_fn_attrs.link_section = Some(val); + } + } + } else if attr.has_name(sym::link_name) { + codegen_fn_attrs.link_name = attr.value_str(); + } else if attr.has_name(sym::link_ordinal) { + link_ordinal_span = Some(attr.span); + if let ordinal @ Some(_) = check_link_ordinal(tcx, attr) { + codegen_fn_attrs.link_ordinal = ordinal; + } + } else if attr.has_name(sym::no_sanitize) { + no_sanitize_span = Some(attr.span); + if let Some(list) = attr.meta_item_list() { + for item in list.iter() { + if item.has_name(sym::address) { + codegen_fn_attrs.no_sanitize |= SanitizerSet::ADDRESS; + } else if item.has_name(sym::cfi) { + codegen_fn_attrs.no_sanitize |= SanitizerSet::CFI; + } else if item.has_name(sym::memory) { + codegen_fn_attrs.no_sanitize |= SanitizerSet::MEMORY; + } else if item.has_name(sym::memtag) { + codegen_fn_attrs.no_sanitize |= SanitizerSet::MEMTAG; + } else if item.has_name(sym::shadow_call_stack) { + codegen_fn_attrs.no_sanitize |= SanitizerSet::SHADOWCALLSTACK; + } else if item.has_name(sym::thread) { + codegen_fn_attrs.no_sanitize |= SanitizerSet::THREAD; + } else if item.has_name(sym::hwaddress) { + codegen_fn_attrs.no_sanitize |= SanitizerSet::HWADDRESS; + } else { + tcx.sess + .struct_span_err(item.span(), "invalid argument for `no_sanitize`") + .note("expected one of: `address`, `cfi`, `hwaddress`, `memory`, `memtag`, `shadow-call-stack`, or `thread`") + .emit(); + } + } + } + } else if attr.has_name(sym::instruction_set) { + codegen_fn_attrs.instruction_set = match attr.meta_kind() { + Some(MetaItemKind::List(ref items)) => match items.as_slice() { + [NestedMetaItem::MetaItem(set)] => { + let segments = + set.path.segments.iter().map(|x| x.ident.name).collect::<Vec<_>>(); + match segments.as_slice() { + [sym::arm, sym::a32] | [sym::arm, sym::t32] => { + if !tcx.sess.target.has_thumb_interworking { + struct_span_err!( + tcx.sess.diagnostic(), + attr.span, + E0779, + "target does not support `#[instruction_set]`" + ) + .emit(); + None + } else if segments[1] == sym::a32 { + Some(InstructionSetAttr::ArmA32) + } else if segments[1] == sym::t32 { + Some(InstructionSetAttr::ArmT32) + } else { + unreachable!() + } + } + _ => { + struct_span_err!( + tcx.sess.diagnostic(), + attr.span, + E0779, + "invalid instruction set specified", + ) + .emit(); + None + } + } + } + [] => { + struct_span_err!( + tcx.sess.diagnostic(), + attr.span, + E0778, + "`#[instruction_set]` requires an argument" + ) + .emit(); + None + } + _ => { + struct_span_err!( + tcx.sess.diagnostic(), + attr.span, + E0779, + "cannot specify more than one instruction set" + ) + .emit(); + None + } + }, + _ => { + struct_span_err!( + tcx.sess.diagnostic(), + attr.span, + E0778, + "must specify an instruction set" + ) + .emit(); + None + } + }; + } else if attr.has_name(sym::repr) { + codegen_fn_attrs.alignment = match attr.meta_item_list() { + Some(items) => match items.as_slice() { + [item] => match item.name_value_literal() { + Some((sym::align, literal)) => { + let alignment = rustc_attr::parse_alignment(&literal.kind); + + match alignment { + Ok(align) => Some(align), + Err(msg) => { + struct_span_err!( + tcx.sess.diagnostic(), + attr.span, + E0589, + "invalid `repr(align)` attribute: {}", + msg + ) + .emit(); + + None + } + } + } + _ => None, + }, + [] => None, + _ => None, + }, + None => None, + }; + } + } + + codegen_fn_attrs.inline = attrs.iter().fold(InlineAttr::None, |ia, attr| { + if !attr.has_name(sym::inline) { + return ia; + } + match attr.meta_kind() { + Some(MetaItemKind::Word) => InlineAttr::Hint, + Some(MetaItemKind::List(ref items)) => { + inline_span = Some(attr.span); + if items.len() != 1 { + struct_span_err!( + tcx.sess.diagnostic(), + attr.span, + E0534, + "expected one argument" + ) + .emit(); + InlineAttr::None + } else if list_contains_name(&items, sym::always) { + InlineAttr::Always + } else if list_contains_name(&items, sym::never) { + InlineAttr::Never + } else { + struct_span_err!( + tcx.sess.diagnostic(), + items[0].span(), + E0535, + "invalid argument" + ) + .help("valid inline arguments are `always` and `never`") + .emit(); + + InlineAttr::None + } + } + Some(MetaItemKind::NameValue(_)) => ia, + None => ia, + } + }); + + codegen_fn_attrs.optimize = attrs.iter().fold(OptimizeAttr::None, |ia, attr| { + if !attr.has_name(sym::optimize) { + return ia; + } + let err = |sp, s| struct_span_err!(tcx.sess.diagnostic(), sp, E0722, "{}", s).emit(); + match attr.meta_kind() { + Some(MetaItemKind::Word) => { + err(attr.span, "expected one argument"); + ia + } + Some(MetaItemKind::List(ref items)) => { + inline_span = Some(attr.span); + if items.len() != 1 { + err(attr.span, "expected one argument"); + OptimizeAttr::None + } else if list_contains_name(&items, sym::size) { + OptimizeAttr::Size + } else if list_contains_name(&items, sym::speed) { + OptimizeAttr::Speed + } else { + err(items[0].span(), "invalid argument"); + OptimizeAttr::None + } + } + Some(MetaItemKind::NameValue(_)) => ia, + None => ia, + } + }); + + // #73631: closures inherit `#[target_feature]` annotations + if tcx.features().target_feature_11 && tcx.is_closure(did.to_def_id()) { + let owner_id = tcx.parent(did.to_def_id()); + if tcx.def_kind(owner_id).has_codegen_attrs() { + codegen_fn_attrs + .target_features + .extend(tcx.codegen_fn_attrs(owner_id).target_features.iter().copied()); + } + } + + // If a function uses #[target_feature] it can't be inlined into general + // purpose functions as they wouldn't have the right target features + // enabled. For that reason we also forbid #[inline(always)] as it can't be + // respected. + if !codegen_fn_attrs.target_features.is_empty() { + if codegen_fn_attrs.inline == InlineAttr::Always { + if let Some(span) = inline_span { + tcx.sess.span_err( + span, + "cannot use `#[inline(always)]` with \ + `#[target_feature]`", + ); + } + } + } + + if !codegen_fn_attrs.no_sanitize.is_empty() { + if codegen_fn_attrs.inline == InlineAttr::Always { + if let (Some(no_sanitize_span), Some(inline_span)) = (no_sanitize_span, inline_span) { + let hir_id = tcx.hir().local_def_id_to_hir_id(did); + tcx.struct_span_lint_hir( + lint::builtin::INLINE_NO_SANITIZE, + hir_id, + no_sanitize_span, + |lint| { + lint.build("`no_sanitize` will have no effect after inlining") + .span_note(inline_span, "inlining requested here") + .emit(); + }, + ) + } + } + } + + // Weak lang items have the same semantics as "std internal" symbols in the + // sense that they're preserved through all our LTO passes and only + // strippable by the linker. + // + // Additionally weak lang items have predetermined symbol names. + if tcx.is_weak_lang_item(did.to_def_id()) { + codegen_fn_attrs.flags |= CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL; + } + if let Some(name) = weak_lang_items::link_name(attrs) { + codegen_fn_attrs.export_name = Some(name); + codegen_fn_attrs.link_name = Some(name); + } + check_link_name_xor_ordinal(tcx, &codegen_fn_attrs, link_ordinal_span); + + // Internal symbols to the standard library all have no_mangle semantics in + // that they have defined symbol names present in the function name. This + // also applies to weak symbols where they all have known symbol names. + if codegen_fn_attrs.flags.contains(CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL) { + codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_MANGLE; + } + + // Any linkage to LLVM intrinsics for now forcibly marks them all as never + // unwinds since LLVM sometimes can't handle codegen which `invoke`s + // intrinsic functions. + if let Some(name) = &codegen_fn_attrs.link_name { + if name.as_str().starts_with("llvm.") { + codegen_fn_attrs.flags |= CodegenFnAttrFlags::NEVER_UNWIND; + } + } + + codegen_fn_attrs +} + +/// Computes the set of target features used in a function for the purposes of +/// inline assembly. +fn asm_target_features<'tcx>(tcx: TyCtxt<'tcx>, did: DefId) -> &'tcx FxHashSet<Symbol> { + let mut target_features = tcx.sess.unstable_target_features.clone(); + if tcx.def_kind(did).has_codegen_attrs() { + let attrs = tcx.codegen_fn_attrs(did); + target_features.extend(&attrs.target_features); + match attrs.instruction_set { + None => {} + Some(InstructionSetAttr::ArmA32) => { + target_features.remove(&sym::thumb_mode); + } + Some(InstructionSetAttr::ArmT32) => { + target_features.insert(sym::thumb_mode); + } + } + } + + tcx.arena.alloc(target_features) +} + +/// Checks if the provided DefId is a method in a trait impl for a trait which has track_caller +/// applied to the method prototype. +fn should_inherit_track_caller(tcx: TyCtxt<'_>, def_id: DefId) -> bool { + if let Some(impl_item) = tcx.opt_associated_item(def_id) + && let ty::AssocItemContainer::ImplContainer = impl_item.container + && let Some(trait_item) = impl_item.trait_item_def_id + { + return tcx + .codegen_fn_attrs(trait_item) + .flags + .intersects(CodegenFnAttrFlags::TRACK_CALLER); + } + + false +} + +fn check_link_ordinal(tcx: TyCtxt<'_>, attr: &ast::Attribute) -> Option<u16> { + use rustc_ast::{Lit, LitIntType, LitKind}; + if !tcx.features().raw_dylib && tcx.sess.target.arch == "x86" { + feature_err( + &tcx.sess.parse_sess, + sym::raw_dylib, + attr.span, + "`#[link_ordinal]` is unstable on x86", + ) + .emit(); + } + let meta_item_list = attr.meta_item_list(); + let meta_item_list: Option<&[ast::NestedMetaItem]> = meta_item_list.as_ref().map(Vec::as_ref); + let sole_meta_list = match meta_item_list { + Some([item]) => item.literal(), + Some(_) => { + tcx.sess + .struct_span_err(attr.span, "incorrect number of arguments to `#[link_ordinal]`") + .note("the attribute requires exactly one argument") + .emit(); + return None; + } + _ => None, + }; + if let Some(Lit { kind: LitKind::Int(ordinal, LitIntType::Unsuffixed), .. }) = sole_meta_list { + // According to the table at https://docs.microsoft.com/en-us/windows/win32/debug/pe-format#import-header, + // the ordinal must fit into 16 bits. Similarly, the Ordinal field in COFFShortExport (defined + // in llvm/include/llvm/Object/COFFImportFile.h), which we use to communicate import information + // to LLVM for `#[link(kind = "raw-dylib"_])`, is also defined to be uint16_t. + // + // FIXME: should we allow an ordinal of 0? The MSVC toolchain has inconsistent support for this: + // both LINK.EXE and LIB.EXE signal errors and abort when given a .DEF file that specifies + // a zero ordinal. However, llvm-dlltool is perfectly happy to generate an import library + // for such a .DEF file, and MSVC's LINK.EXE is also perfectly happy to consume an import + // library produced by LLVM with an ordinal of 0, and it generates an .EXE. (I don't know yet + // if the resulting EXE runs, as I haven't yet built the necessary DLL -- see earlier comment + // about LINK.EXE failing.) + if *ordinal <= u16::MAX as u128 { + Some(*ordinal as u16) + } else { + let msg = format!("ordinal value in `link_ordinal` is too large: `{}`", &ordinal); + tcx.sess + .struct_span_err(attr.span, &msg) + .note("the value may not exceed `u16::MAX`") + .emit(); + None + } + } else { + tcx.sess + .struct_span_err(attr.span, "illegal ordinal format in `link_ordinal`") + .note("an unsuffixed integer value, e.g., `1`, is expected") + .emit(); + None + } +} + +fn check_link_name_xor_ordinal( + tcx: TyCtxt<'_>, + codegen_fn_attrs: &CodegenFnAttrs, + inline_span: Option<Span>, +) { + if codegen_fn_attrs.link_name.is_none() || codegen_fn_attrs.link_ordinal.is_none() { + return; + } + let msg = "cannot use `#[link_name]` with `#[link_ordinal]`"; + if let Some(span) = inline_span { + tcx.sess.span_err(span, msg); + } else { + tcx.sess.err(msg); + } +} + +/// Checks the function annotated with `#[target_feature]` is not a safe +/// trait method implementation, reporting an error if it is. +fn check_target_feature_trait_unsafe(tcx: TyCtxt<'_>, id: LocalDefId, attr_span: Span) { + let hir_id = tcx.hir().local_def_id_to_hir_id(id); + let node = tcx.hir().get(hir_id); + if let Node::ImplItem(hir::ImplItem { kind: hir::ImplItemKind::Fn(..), .. }) = node { + let parent_id = tcx.hir().get_parent_item(hir_id); + let parent_item = tcx.hir().expect_item(parent_id.def_id); + if let hir::ItemKind::Impl(hir::Impl { of_trait: Some(_), .. }) = parent_item.kind { + tcx.sess + .struct_span_err( + attr_span, + "`#[target_feature(..)]` cannot be applied to safe trait method", + ) + .span_label(attr_span, "cannot be applied to safe trait method") + .span_label(tcx.def_span(id), "not an `unsafe` function") + .emit(); + } + } +} |